diff --git a/sync/migrations/0007_dataaccess_store_id.py b/sync/migrations/0007_dataaccess_store_id.py
new file mode 100644
index 0000000..8113e21
--- /dev/null
+++ b/sync/migrations/0007_dataaccess_store_id.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.1 on 2025-06-12 13:57
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('sync', '0006_alter_modellog_operation'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='dataaccess',
+            name='store_id',
+            field=models.CharField(default='', max_length=100),
+        ),
+    ]
diff --git a/sync/migrations/0008_alter_dataaccess_store_id.py b/sync/migrations/0008_alter_dataaccess_store_id.py
new file mode 100644
index 0000000..d89a922
--- /dev/null
+++ b/sync/migrations/0008_alter_dataaccess_store_id.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.1 on 2025-06-26 12:20
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('sync', '0007_dataaccess_store_id'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='dataaccess',
+            name='store_id',
+            field=models.CharField(blank=True, default='', max_length=100, null=True),
+        ),
+    ]
diff --git a/sync/model_manager.py b/sync/model_manager.py
new file mode 100644
index 0000000..531ca14
--- /dev/null
+++ b/sync/model_manager.py
@@ -0,0 +1,194 @@
+from django.conf import settings
+
+from typing import List, Dict
+from .registry import model_registry
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+class SyncModelChildrenManager:
+    """
+    Manager class for handling model children sharing configuration.
+    Reads the SYNC_MODEL_CHILDREN_SHARING setting once and builds a bidirectional
+    relationship graph for efficient lookup.
+    """
+
+    def __init__(self):
+        """Initialize the manager by reading the Django setting and building the relationship graph."""
+        self._model_relationships = getattr(
+            settings,
+            'SYNC_MODEL_CHILDREN_SHARING',
+            {}
+        )
+        self._relationship_graph = {}
+
+    def _build_relationship_graph(self) -> Dict[str, List[List[str]]]:
+        """
+        Build a bidirectional relationship graph.
+
+        Returns:
+            Dict[str, List[List[str]]]: Dictionary where keys are model names and values
+            are lists of relationship paths (arrays of relationship names).
+        """
+        graph = {}
+
+        # Add direct relationships (original models to their children)
+        for model_name, relationships in self._model_relationships.items():
+            if model_name not in graph:
+                graph[model_name] = []
+            graph[model_name].append(relationships)
+
+        # Build reverse relationships (children back to original models)
+        for original_model_name, relationships in self._model_relationships.items():
+
+            try:
+                current_model = model_registry.get_model(original_model_name)
+                if current_model is None:
+                    print(f'missing {original_model_name}')
+                    continue
+
+                current_reverse_path = []
+
+                for relationship_name in relationships:
+                    # Get the related model through _meta
+                    try:
+                        field = None
+                        # Try to find the field in the model's _meta
+                        for f in current_model._meta.get_fields():
+                            if hasattr(f, 'related_name') and f.related_name == relationship_name:
+                                field = f
+                                break
+                            elif hasattr(f, 'name') and f.name == relationship_name:
+                                field = f
+                                break
+
+                        if field is None:
+                            continue
+
+                        # Get the related model
+                        if hasattr(field, 'related_model'):
+                            related_model = field.related_model
+                        elif hasattr(field, 'model'):
+                            related_model = field.model
+                        else:
+                            continue
+
+                        related_model_name = related_model.__name__
+
+                        # Find the reverse relationship name
+                        reverse_relationship_name = self._find_reverse_relationship(
+                            relationship_name, current_model, related_model
+                        )
+
+                        if reverse_relationship_name:
+                            current_reverse_path.append(reverse_relationship_name)
+                            # Add the reverse path
+                            if related_model_name not in graph:
+                                graph[related_model_name] = []
+
+                            # The path back is just the reverse relationship name
+                            graph[related_model_name].append(current_reverse_path[::-1]) # make a reverse copy
+
+                        current_model = related_model
+
+                    except Exception as e:
+                        logger.info(f'error 2 > {e}')
+                        # Skip problematic relationships
+                        continue
+
+            except Exception as e:
+                logger.info(f'error > {e}')
+                continue
+
+        return graph
+
+    def _find_reverse_relationship(self, original_relationship_name, in_model, for_model):
+        """
+        Find the reverse relationship name from from_model to to_model.
+
+        Args:
+            from_model: The model to search relationships from
+            to_model: The target model to find relationship to
+            original_relationship_name: The original relationship name for context
+
+        Returns:
+            str or None: The reverse relationship name if found
+        """
+
+        print(f'reverse of {original_relationship_name} in = {in_model} for {for_model} ')
+        try:
+            for field in for_model._meta.get_fields():
+                # Check ForeignKey, OneToOneField fields
+                # print(f'{for_model} : field name = {field.name} / field.related_model = {field.related_model == in_model}')
+                if hasattr(field, 'related_model') and field.related_model == in_model:
+                    return field.name
+                    ### possible improvements to do here if multiple relationships of the same type
+
+
+                    # Check if this field has a related_name that matches our original relationship
+                    # if hasattr(field, 'related_name') and field.related_name == original_relationship_name:
+                    #     # This is the reverse of our original relationship
+                    #     return field.name
+                    # elif not hasattr(field, 'related_name') or field.related_name is None:
+                    #     default_name = f"{in_model._meta.related_query_name}"
+                    #     print(f'no related name: {default_name} / {original_relationship_name.rstrip('s')} ')
+                    #     if default_name == original_relationship_name.rstrip('s'):  # Simple heuristic
+                    #         return field.name
+
+                # Check reverse relationships
+                if hasattr(field, 'field') and hasattr(field.field, 'model'):
+                    if field.field.model == in_model:
+                        if field.get_accessor_name() == original_relationship_name:
+                            return field.field.name
+
+        except Exception as e:
+            print(f'!! ERROR = {e}')
+            pass
+
+        return None
+
+    def get_relationships(self, model_name: str) -> List[str]:
+        """
+        Get the list of direct relationships for a given model name.
+
+        Args:
+            model_name (str): The name of the model to look up
+
+        Returns:
+            List[str]: List of relationship names for the model.
+                      Returns empty list if model is not found.
+        """
+
+        return self._model_relationships.get(model_name, [])
+
+    def get_relationship_paths(self, model_name: str) -> List[List[str]]:
+        """
+        Get all relationship paths for a given model name.
+        This includes both direct relationships and reverse paths.
+
+        Args:
+            model_name (str): The name of the model to look up
+
+        Returns:
+            List[List[str]]: List of relationship paths (each path is a list of relationship names).
+                            Returns empty list if model is not found.
+        """
+        if not self._relationship_graph:
+            self._relationship_graph = self._build_relationship_graph()
+        # logger.info(f'self._relationship_graph = {self._relationship_graph}')
+
+        return self._relationship_graph.get(model_name, [])
+
+    def get_relationship_graph(self) -> Dict[str, List[List[str]]]:
+        """
+        Get the complete relationship graph.
+
+        Returns:
+            Dict[str, List[List[str]]]: The complete relationship graph
+        """
+        return self._relationship_graph.copy()
+
+
+# Create a singleton instance to use throughout the application
+sync_model_manager = SyncModelChildrenManager()
diff --git a/sync/models/base.py b/sync/models/base.py
index 8668e9d..562dd56 100644
--- a/sync/models/base.py
+++ b/sync/models/base.py
@@ -1,9 +1,13 @@
 from django.db import models
 from django.utils.timezone import now
 from django.conf import settings
+
 from typing import List, Set
+from ..model_manager import sync_model_manager
+
+import logging
 
-from django.apps import apps
+logger = logging.getLogger(__name__)
 
 class BaseModel(models.Model):
     creation_date = models.DateTimeField(default=now, editable=False)
@@ -28,22 +32,28 @@ class BaseModel(models.Model):
         else:
             return None
 
+    def data_identifier_dict(self):
+        return {
+            'model_id': self.id,
+            'store_id': None
+        }
+
     def update_data_access_list(self):
-        related_instances = self.related_instances()
-        related_ids = [ri.id for ri in related_instances]
-        related_ids.append(self.id)
-
-        DataAccess = apps.get_model('sync', 'DataAccess')
-        data_accesses = DataAccess.objects.filter(model_id__in=related_ids)
-        for data_access in data_accesses:
-            self.add_data_access_relation(data_access)
-
-        # add data_access to children who might not had the relationship
-        # if data_accesses:
-        #     for child in self.get_children_by_model():
-        #         if len(child.data_access_ids) == 0:
-        #             for data_access in data_accesses:
-        #                 self.add_data_access_relation(data_access)
+        related_instances = self.sharing_related_instances()
+        data_access_ids = set()
+        for instance in related_instances:
+            if isinstance(instance, BaseModel) and instance.data_access_ids:
+                data_access_ids.update(instance.data_access_ids)
+
+        # print(f'related_instances = {related_instances}')
+        # data_access_ids = [instance.data_access_ids for instance in related_instances if isinstance(instance, BaseModel)]
+        # data_access_ids.extend(self.data_access_ids)
+        self.data_access_ids = list(data_access_ids)
+
+        # DataAccess = apps.get_model('sync', 'DataAccess')
+        # data_accesses = DataAccess.objects.filter(model_id__in=related_ids)
+        # for data_access in data_accesses:
+        #     self.add_data_access_relation(data_access)
 
     def add_data_access_relation(self, data_access):
         str_id = str(data_access.id)
@@ -187,8 +197,64 @@ class BaseModel(models.Model):
 
         return None
 
+    def sharing_related_instances(self):
+        """
+        Get all related instances (both children and parents) recursively
+        """
+        instances = []
+        processed_objects = set()
+        instances.extend(self.get_shared_children(processed_objects))
+
+        processed_objects = set()
+        instances.extend(self.get_recursive_parents(processed_objects))
+
+        return instances
+
+    def get_shared_children(self, processed_objects):
+        relationships_arrays = sync_model_manager.get_relationship_paths(self.__class__.__name__)
+        instances = []
+
+        if relationships_arrays:
+            for relationships in relationships_arrays:
+                children = self.get_shared_children_from_relationships(relationships, processed_objects)
+                instances.extend(children)
+        else:
+            instances.extend(self.get_recursive_children(processed_objects))
+
+        return instances
+
+    def get_shared_children_from_relationships(self, relationships, processed_objects):
+
+        print(f'>>> {self.__class__.__name__} : relationships = {relationships}')
+        current = [self]
+        for relationship in relationships:
+            # print(f'> relationship = {relationship}')
+            values = []
+            for item in current:
+                value = getattr(item, relationship)
+
+                if hasattr(value, 'all') and callable(value.all):
+                    # This is a queryset from a reverse relationship
+                    for related_obj in value.all():
+                        processed_objects.add(related_obj)
+                    values.extend(value.all())
+                else:
+                    processed_objects.add(value)
+
+                    values.append(value)
+            current = values
+
+        # logger.info(f'+++ shared children = {processed_objects}')
+        return processed_objects
+
 class SideStoreModel(BaseModel):
     store_id = models.CharField(max_length=100, default="") # a value matching LeStorage directory sub-stores. Matches the name of the directory.
 
     class Meta:
         abstract = True
+
+    def data_identifier_dict(self):
+        return {
+            'model_id': self.id,
+            'store_id': self.store_id
+        }
diff --git a/sync/models/data_access.py b/sync/models/data_access.py
index 5a38ae3..bc2507c 100644
--- a/sync/models/data_access.py
+++ b/sync/models/data_access.py
@@ -1,13 +1,13 @@
 from django.db import models
 from django.utils import timezone
-# from django.apps import apps
 from django.core.exceptions import ObjectDoesNotExist
 from django.conf import settings
+from django.db import transaction
 
 from ..registry import model_registry
 import uuid
 
-from . import ModelLog, SideStoreModel, BaseModel
+from . import ModelLog, BaseModel
 import logging
 
 logger = logging.getLogger(__name__)
@@ -17,6 +17,7 @@ class DataAccess(BaseModel):
     shared_with = models.ManyToManyField(settings.AUTH_USER_MODEL, related_name='shared_data')
     model_name = models.CharField(max_length=50)
     model_id = models.UUIDField()
+    store_id = models.CharField(max_length=100, default="", blank=True, null=True) # a value matching LeStorage directory sub-stores. Matches the name of the directory.
     granted_at = models.DateTimeField(auto_now_add=True)
 
     def delete_dependencies(self):
@@ -35,33 +36,31 @@ class DataAccess(BaseModel):
         """Create an access log for a list of users """
         model_class = model_registry.get_model(self.model_name)
         if model_class:
-            try:
-                obj = model_class.objects.get(id=self.model_id)
-                store_id = None
-                if isinstance(obj, SideStoreModel):
-                    store_id = obj.store_id
-
-                for user in users:
+            for user in users:
+                logger.info(f'=== create ModelLog for: {operation} > {users}')
+                ModelLog.objects.create(
+                    user=user,
+                    model_id=self.model_id,
+                    model_name=self.model_name,
+                    operation=operation,
+                    date=timezone.now(),
+                    store_id=self.store_id
+                )
 
-                    logger.info(f'=== create ModelLog for: {operation} > {users}')
-
-                    existing_log = ModelLog.objects.filter(user=user, model_id=self.model_id, operation=operation).first()
-                    if existing_log:
-                        existing_log.date = timezone.now()
-                        existing_log.model_operation = operation
-                        existing_log.save()
-                    else:
-                        ModelLog.objects.create(
-                            user=user,
-                            model_id=self.model_id,
-                            model_name=self.model_name,
-                            operation=operation,
-                            date=timezone.now(),
-                            store_id=store_id
-                        )
-            except ObjectDoesNotExist:
-                logger.warn(f'!!! object does not exists any more: {self.model_name} : {self.model_id} : {operation}')
-                pass
+                # existing_log = ModelLog.objects.filter(user=user, model_id=self.model_id, operation=operation).first()
+                # if existing_log:
+                #     existing_log.date = timezone.now()
+                #     existing_log.model_operation = operation
+                #     existing_log.save()
+                # else:
+                #     ModelLog.objects.create(
+                #         user=user,
+                #         model_id=self.model_id,
+                #         model_name=self.model_name,
+                #         operation=operation,
+                #         date=timezone.now(),
+                #         store_id=self.store_id
+                #     )
         else:
             logger.warn(f'!!!model not found: {self.model_name}')
 
@@ -70,12 +69,15 @@ class DataAccess(BaseModel):
         if model_class:
             try:
                 obj = model_class.objects.get(id=self.model_id)
-                related_instance = obj.related_instances()
+                related_instance = obj.sharing_related_instances() # here we want instances granted by the DataAccess, including SYNC_MODEL_CHILDREN_SHARING
                 related_instance.append(obj)
-                for instance in related_instance:
-                    if isinstance(instance, BaseModel):
-                        instance.add_data_access_relation(self)
-                        instance.save()
+
+                with transaction.atomic():
+                    for instance in related_instance:
+                        logger.info(f'adds DataAccess to {instance.__class__.__name__}')
+                        if isinstance(instance, BaseModel):
+                            instance.add_data_access_relation(self)
+                            instance.save()
             except ObjectDoesNotExist:
                 pass
 
@@ -86,9 +88,11 @@ class DataAccess(BaseModel):
                 obj = model_class.objects.get(id=self.model_id)
                 related_instance = obj.related_instances()
                 related_instance.append(obj)
-                for instance in related_instance:
-                    if isinstance(instance, BaseModel):
-                        instance.remove_data_access_relation(self)
-                        instance.save()
+
+                with transaction.atomic():
+                    for instance in related_instance:
+                        if isinstance(instance, BaseModel):
+                            instance.remove_data_access_relation(self)
+                            instance.save()
             except ObjectDoesNotExist:
                 pass
diff --git a/sync/registry.py b/sync/registry.py
index f27b2e2..881f2d6 100644
--- a/sync/registry.py
+++ b/sync/registry.py
@@ -1,22 +1,25 @@
 from django.conf import settings
 from django.apps import apps
-from .models import BaseModel
 from django.contrib.auth import get_user_model
+
 import threading
+import logging
+import importlib
 
-User = get_user_model()
+logger = logging.getLogger(__name__)
 
 class ModelRegistry:
     def __init__(self):
         self._registry = {}
 
     def load_sync_apps(self):
+        base_model = get_abstract_model_class('BaseModel')
         sync_apps = getattr(settings, 'SYNC_APPS', {})
         for app_label, config in sync_apps.items():
             app_models = apps.get_app_config(app_label).get_models()
             for model in app_models:
                 if hasattr(model, '_meta') and not model._meta.abstract:
-                    if issubclass(model, BaseModel) or model == User:
+                    if issubclass(model, base_model) or model == get_user_model():
                         model_name = model.__name__
                         if self.should_sync_model(model_name, config):
                             self.register(model)
@@ -39,6 +42,10 @@ class ModelRegistry:
 # Global instance
 model_registry = ModelRegistry()
 
+def get_abstract_model_class(model_name):
+    module = importlib.import_module('sync.models')
+    return getattr(module, model_name)
+
 class DeviceRegistry:
     """Thread-safe registry to track device IDs associated with model instances."""
 
diff --git a/sync/signals.py b/sync/signals.py
index e0c0fba..acce299 100644
--- a/sync/signals.py
+++ b/sync/signals.py
@@ -11,6 +11,7 @@ from .ws_sender import websocket_sender
 from .registry import device_registry, related_users_registry
 
 import logging
+import traceback
 
 logger = logging.getLogger(__name__)
 
@@ -21,28 +22,25 @@ User = get_user_model()
 @receiver([pre_save, pre_delete])
 def presave_handler(sender, instance, **kwargs):
 
-    # some other classes are excluded in settings_app.py: SYNC_APPS
-    if not isinstance(instance, (BaseModel, User)):
-        return
-
-    signal = kwargs.get('signal')
-    # avoid crash in manage.py createsuperuser + delete user in the admin
-    if isinstance(instance, User) and (instance._state.db is None or signal == pre_delete):
-        return
-
-    users = related_users(instance)
+    try:
+        # some other classes are excluded in settings_app.py: SYNC_APPS
+        if not isinstance(instance, (BaseModel, User)) or isinstance(instance, DataAccess):
+            return
 
-    related_users_registry.register(instance.id, users)
-    # user_ids = [user.id for user in users]
+        signal = kwargs.get('signal')
+        # avoid crash in manage.py createsuperuser + delete user in the admin
+        if isinstance(instance, User) and (instance._state.db is None or signal == pre_delete):
+            return
 
+        users = related_users(instance)
+        related_users_registry.register(instance.id, users)
 
-    if signal == pre_save:
-        detect_foreign_key_changes_for_shared_instances(sender, instance)
-        sig_type = 'pre_save'
-    else:
-        sig_type = 'pre_delete'
-    logger.info(f'* {sig_type} : {instance.__class__.__name__} > impacted users = {users}')
+        if signal == pre_save:
+            detect_foreign_key_changes_for_shared_instances(sender, instance)
 
+    except Exception as e:
+        logger.info(f'*** presave_handler ERROR: {e}')
+        raise
 
 @receiver([post_save, post_delete])
 def synchronization_notifications(sender, instance, created=False, **kwargs):
@@ -56,47 +54,31 @@ def synchronization_notifications(sender, instance, created=False, **kwargs):
     if not isinstance(instance, BaseModel) and not isinstance(instance, User):
         return
 
-    process_foreign_key_changes(sender, instance, **kwargs)
-
-    signal = kwargs.get('signal')
-    save_model_log_if_possible(instance, signal, created)
-    notify_impacted_users(instance)
-
-    related_users_registry.unregister(instance.id)
+    try:
+        process_foreign_key_changes(sender, instance, **kwargs)
+        signal = kwargs.get('signal')
+        save_model_log_if_possible(instance, signal, created)
+        notify_impacted_users(instance)
+        related_users_registry.unregister(instance.id)
+    except Exception as e:
+        logger.info(f'*** ERROR2: {e}')
+        logger.info(traceback.format_exc())
+        raise
 
 def notify_impacted_users(instance):
-    # print(f'*** notify_impacted_users for instance: {instance}')
-    # user_ids = set()
-    # # add impacted users
-    # if isinstance(instance, User):
-    #     user_ids.add(instance.id)
-    # elif isinstance(instance, BaseModel):
-    #     owner = instance.last_updated_by
-    #     if owner:
-    #         user_ids.add(owner.id)
-
-    # if isinstance(instance, BaseModel):
-    #     if hasattr(instance, '_users_to_notify'):
-    #         user_ids.update(instance._users_to_notify)
-    #     else:
-    #         print('no users to notify')
-
     device_id = device_registry.get_device_id(instance.id)
     users = related_users_registry.get_users(instance.id)
 
     if users:
         user_ids = [user.id for user in users]
         websocket_sender.send_message(user_ids, device_id)
-        # print(f'notify device: {device_id}, users = {user_ids}')
-        # for user_id in user_ids:
-        #     websocket_sender.send_user_message(user_id, device_id)
 
     device_registry.unregister(instance.id)
 
 def save_model_log_if_possible(instance, signal, created):
 
     users = related_users_registry.get_users(instance.id)
-    logger.debug(f'*** save_model_log_if_possible >>> users from registry = {users}, instance = {instance}')
+    # logger.info(f'*** save_model_log_if_possible >>> users from registry = {users}, instance = {instance}')
 
     if not users:
         logger.warning(f'!!! Registry returned empty users for instance {instance.id} ({instance.__class__.__name__})')
@@ -118,8 +100,8 @@ def save_model_log_if_possible(instance, signal, created):
         if isinstance(instance, SideStoreModel):
             store_id = instance.store_id
 
-        if operation == ModelOperation.DELETE: # delete now unnecessary logs
-            ModelLog.objects.filter(model_id=instance.id).delete()
+        # if operation == ModelOperation.DELETE: # delete now unnecessary logs
+            # ModelLog.objects.filter(model_id=instance.id).delete()
 
         # user_ids = [user.id for user in users]
         # # print(f'users to notify: {user_ids}')
@@ -130,16 +112,14 @@ def save_model_log_if_possible(instance, signal, created):
         logger.info(f'!!! Model Log could not be created because no linked user could be found: {instance.__class__.__name__} {instance}, {signal}')
 
 def save_model_log(users, model_operation, model_name, model_id, store_id):
-
     device_id = device_registry.get_device_id(model_id)
-
-    logger.info(f'*** creating ModelLogs for: {model_operation} {model_name} : {users}')
+    # logger.info(f'*** creating ModelLogs for: {model_operation} {model_name} : {users}')
 
     try:
         with transaction.atomic():
             created_logs = []
             for user in users:
-                logger.debug(f'Creating ModelLog for user {user.id} ({user.username})')
+                # logger.info(f'Creating ModelLog for user {user.id} - user exists: {User.objects.filter(id=user.id).exists()}')
                 model_log = ModelLog(
                     user=user,
                     operation=model_operation,
@@ -149,20 +129,19 @@ def save_model_log(users, model_operation, model_name, model_id, store_id):
                     device_id=device_id
                 )
                 model_log.save()
+                # logger.info(f'ModelLog saved with ID: {model_log.id}')
                 created_logs.append(model_log.id)
-                logger.debug(f'Successfully created ModelLog {model_log.id}')
 
-            logger.info(f'*** Successfully created {len(created_logs)} ModelLogs: {created_logs}')
+            # Immediate verification within transaction
+            immediate_count = ModelLog.objects.filter(id__in=created_logs).count()
+            # logger.info(f'*** Within transaction: Created {len(created_logs)}, found {immediate_count}')
 
-            # Verify ModelLogs were actually persisted
-            persisted_count = ModelLog.objects.filter(id__in=created_logs).count()
-            if persisted_count != len(created_logs):
-                logger.error(f'*** PERSISTENCE VERIFICATION FAILED! Created {len(created_logs)} ModelLogs but only {persisted_count} were persisted to database')
-            else:
-                logger.debug(f'*** PERSISTENCE VERIFIED: All {persisted_count} ModelLogs successfully persisted')
+        # Verification after transaction commits
+        persisted_count = ModelLog.objects.filter(id__in=created_logs).count()
+        # logger.info(f'*** After transaction: Created {len(created_logs)}, persisted {persisted_count}')
 
     except Exception as e:
-        logger.error(f'*** FAILED to create ModelLogs for: {model_operation} {model_name}, users: {[u.id for u in users]}, error: {e}', exc_info=True)
+        logger.error(f'*** Exception during ModelLog creation: {e}', exc_info=True)
         raise
 
     # with transaction.atomic():
@@ -206,7 +185,6 @@ def detect_foreign_key_changes_for_shared_instances(sender, instance):
         return
 
     data_access_list = related_data_access(instance)
-    # print(f'FK change > DA count = {len(data_access_list)}')
     if data_access_list:
         try:
             old_instance = sender.objects.get(pk=instance.pk)
@@ -280,7 +258,8 @@ def delete_data_access_if_necessary(sender, instance, **kwargs):
     if not isinstance(instance, BaseModel):
         return
     if hasattr(instance, 'id'):
-        DataAccess.objects.filter(model_id=instance.id).delete()
+        for data_access in DataAccess.objects.filter(model_id=instance.id):
+            data_access.create_revoke_access_log()
 
 @receiver(m2m_changed, sender=DataAccess.shared_with.through)
 def handle_shared_with_changes(sender, instance, action, pk_set, **kwargs):
@@ -306,26 +285,41 @@ def handle_shared_with_changes(sender, instance, action, pk_set, **kwargs):
 
 @receiver(post_save, sender=DataAccess)
 def data_access_post_save(sender, instance, **kwargs):
-    instance.add_references() # create DataAccess references on hierarchy
+    try:
+        instance.add_references() # create DataAccess references on hierarchy
 
-    if instance.related_user:
-        evaluate_if_user_should_sync(instance.related_user)
+        if instance.related_user:
+            evaluate_if_user_should_sync(instance.related_user)
+    except Exception as e:
+        logger.info(f'*** ERROR3: {e}')
+        logger.info(traceback.format_exc())
+        raise
 
 @receiver(pre_delete, sender=DataAccess)
 def revoke_access_after_delete(sender, instance, **kwargs):
-    instance.cleanup_references()
-    instance.create_revoke_access_log()
-    related_users_registry.register(instance.id, instance.shared_with.all())
+    try:
+        instance.cleanup_references()
+        instance.create_revoke_access_log()
+        related_users_registry.register(instance.id, instance.shared_with.all())
 
-    instance._user = instance.related_user
+        instance._user = instance.related_user
+    except Exception as e:
+        logger.info(f'*** ERROR4: {e}')
+        logger.info(traceback.format_exc())
+        raise
 
 @receiver(post_delete, sender=DataAccess)
 def data_access_post_delete(sender, instance, **kwargs):
-    notify_impacted_users(instance)
+    try:
+        notify_impacted_users(instance)
 
-    if not hasattr(instance, '_user') or not instance._user:
-        return
-    evaluate_if_user_should_sync(instance._user)
+        if not hasattr(instance, '_user') or not instance._user:
+            return
+        evaluate_if_user_should_sync(instance._user)
+    except Exception as e:
+        logger.info(f'*** ERROR5: {e}')
+        logger.info(traceback.format_exc())
+        raise
 
 def related_users(instance):
     users = set()
@@ -334,12 +328,10 @@ def related_users(instance):
     elif isinstance(instance, BaseModel):
         users.add(instance.related_user)
         data_access_list = DataAccess.objects.filter(id__in=instance.data_access_ids)
-
         # print(f'instance = {instance.__class__.__name__}, data access count = {len(data_access_list)}')
         for data_access in data_access_list:
             users.add(data_access.related_user)
             users.update(data_access.shared_with.all())
-
         if isinstance(instance, DataAccess):
             users.update(instance.shared_with.all())
 
@@ -370,9 +362,14 @@ def evaluate_if_user_should_sync(user):
 
 @receiver(post_save, sender=Device)
 def device_created(sender, instance, **kwargs):
-    if not instance.user:
-        return
-    evaluate_if_user_should_sync(instance.user)
+    try:
+        if not instance.user:
+            return
+        evaluate_if_user_should_sync(instance.user)
+    except Exception as e:
+        logger.info(f'*** ERROR6: {e}')
+        logger.info(traceback.format_exc())
+        raise
 
 @receiver(pre_delete, sender=Device)
 def device_pre_delete(sender, instance, **kwargs):
@@ -380,6 +377,11 @@ def device_pre_delete(sender, instance, **kwargs):
 
 @receiver(post_delete, sender=Device)
 def device_post_delete(sender, instance, **kwargs):
-    if not hasattr(instance, '_user') or not instance._user:
-        return
-    evaluate_if_user_should_sync(instance._user)
+    try:
+        if not hasattr(instance, '_user') or not instance._user:
+            return
+        evaluate_if_user_should_sync(instance._user)
+    except Exception as e:
+        logger.info(f'*** ERROR7: {e}')
+        logger.info(traceback.format_exc())
+        raise
diff --git a/sync/utils.py b/sync/utils.py
index ee7ff80..bcba5b4 100644
--- a/sync/utils.py
+++ b/sync/utils.py
@@ -1,7 +1,7 @@
 import importlib
-from django.apps import apps
-from .registry import model_registry
 from collections import defaultdict
+from .registry import model_registry
+from .models import BaseModel, SideStoreModel
 
 import random
 import string
@@ -50,6 +50,7 @@ class HierarchyOrganizer:
     def __init__(self):
         self.levels = []  # List of dictionaries, each representing a level
         self.item_levels = {}  # Keep track of items and their levels: (model_name, id) -> level
+        self.children = set()
 
     def add_item(self, model_name, item_data, level):
         """
@@ -90,3 +91,42 @@ class HierarchyOrganizer:
             if cleaned_dict:
                 cleaned_levels.append(cleaned_dict)
         return cleaned_levels
+
+    def add_relations(self, instance):
+        self.add_related_parents(instance)
+        self.add_related_children(instance)
+
+    def add_related_children(self, instance):
+        instance.get_shared_children(self.children)
+
+    def grouped_children(self):
+        grouped = defaultdict(list)
+        for instance in self.children:
+            class_name = instance.__class__.__name__
+            grouped[class_name].append(instance.data_identifier_dict())
+        return dict(grouped)
+
+    def add_related_parents(self, instance, current_level=0):
+        """
+        Recursively add all parents of an instance to the hierarchy organizer.
+        Parents are added at a higher level than their children.
+        """
+        parent_models = instance.get_parents_by_model()
+
+        for parent_model_name, parent in parent_models.items():
+            if isinstance(parent, BaseModel):
+                store_id = None
+                if isinstance(parent, SideStoreModel):
+                    store_id = parent.store_id
+
+                parent_data = {
+                    'model_id': parent.id,
+                    'store_id': store_id
+                }
+
+                # Add parent at the next level
+                # print(f'*** add parent: {parent_model_name}: {parent.id}')
+                self.add_item(parent_model_name, parent_data, current_level + 1)
+
+                # Recursively process parent's parents
+                self.add_related_parents(parent, current_level + 1)
diff --git a/sync/views.py b/sync/views.py
index 3f27041..d8a27c9 100644
--- a/sync/views.py
+++ b/sync/views.py
@@ -24,15 +24,38 @@ from .models import ModelLog, BaseModel, SideStoreModel, DataAccess
 from .registry import model_registry, device_registry
 from .ws_sender import websocket_sender
 
+import logging
+
+logger = logging.getLogger(__name__)
+
 # class HierarchyApiView(APIView):
 
+def instances_to_dict(instances, models_dict):
+    for instance in instances:
+        child_model_name = instance.__class__.__name__
+        serializer = get_serializer(instance, child_model_name)
+        if child_model_name not in models_dict:
+            models_dict[child_model_name] = {}
+
+        models_dict[child_model_name][instance.id] = serializer.data
+    return models_dict
+
+def instances_to_data_identifier_dict(instances, models_dict):
+    for instance in instances:
+        if isinstance(instance, BaseModel):
+            child_model_name = instance.__class__.__name__
+            if child_model_name not in models_dict:
+                models_dict[child_model_name] = {}
+            models_dict[child_model_name][instance.id] = instance.data_identifier_dict()
+    return models_dict
+
 def add_children_hierarchy(instance, models_dict):
     sync_models = getattr(settings, 'SYNC_MODEL_CHILDREN_SHARING', {})
     if instance.__class__.__name__ in sync_models:
         relationships = sync_models[instance.__class__.__name__]
         #     'Match': {'team_scores', 'team_registration', 'player_registrations'}
 
-        print(f'relationships = {relationships}')
+        # print(f'relationships = {relationships}')
         current = [instance]
         for relationship in relationships:
             print(f'> relationship = {relationship}')
@@ -75,30 +98,30 @@ def add_children_recursively(instance, models_dict):
                 models_dict[child_model_name][child.id] = serializer.data
                 add_children_recursively(child, models_dict)
 
-def add_parents_with_hierarchy_organizer(instance, hierarchy_organizer, current_level=0):
-    """
-    Recursively add all parents of an instance to the hierarchy organizer.
-    Parents are added at a higher level than their children.
-    """
-    parent_models = instance.get_parents_by_model()
+# def add_parents_with_hierarchy_organizer(instance, hierarchy_organizer, current_level=0):
+#     """
+#     Recursively add all parents of an instance to the hierarchy organizer.
+#     Parents are added at a higher level than their children.
+#     """
+#     parent_models = instance.get_parents_by_model()
 
-    for parent_model_name, parent in parent_models.items():
-        if isinstance(parent, BaseModel):
-            store_id = None
-            if isinstance(parent, SideStoreModel):
-                store_id = parent.store_id
+#     for parent_model_name, parent in parent_models.items():
+#         if isinstance(parent, BaseModel):
+#             store_id = None
+#             if isinstance(parent, SideStoreModel):
+#                 store_id = parent.store_id
 
-            parent_data = {
-                'model_id': parent.id,
-                'store_id': store_id
-            }
+#             parent_data = {
+#                 'model_id': parent.id,
+#                 'store_id': store_id
+#             }
 
-            # Add parent at the next level
-            print(f'*** add parent: {parent_model_name}: {parent.id}')
-            hierarchy_organizer.add_item(parent_model_name, parent_data, current_level + 1)
+#             # Add parent at the next level
+#             print(f'*** add parent: {parent_model_name}: {parent.id}')
+#             hierarchy_organizer.add_item(parent_model_name, parent_data, current_level + 1)
 
-            # Recursively process parent's parents
-            add_parents_with_hierarchy_organizer(parent, hierarchy_organizer, current_level + 1)
+#             # Recursively process parent's parents
+#             add_parents_with_hierarchy_organizer(parent, hierarchy_organizer, current_level + 1)
 
 def add_parents_recursively(instance, dictionary):
     """
@@ -336,14 +359,17 @@ class LogProcessingResult:
         shared = defaultdict(dict)
         grants = defaultdict(dict)
 
+        try:
         # Process each grant instance
-        for model_name, instances in self.shared_instances.items():
-            for model_id, instance in instances.items():
-                serializer = get_serializer(instance, model_name)
-                shared[model_name][model_id] = serializer.data
+            for model_name, instances in self.shared_instances.items():
+                for model_id, instance in instances.items():
+                    serializer = get_serializer(instance, model_name)
+                    shared[model_name][model_id] = serializer.data
 
-                add_children_hierarchy(instance, grants)
-                add_parents_recursively(instance, grants)
+                    add_children_hierarchy(instance, grants)
+                    add_parents_recursively(instance, grants)
+        except Exception as e:
+            print(f'ERR = {e}')
 
         # Convert to lists
         for model_name in shared:
@@ -356,44 +382,50 @@ class LogProcessingResult:
     def process_revocations(self):
         """Process revocations and their hierarchies."""
         revocations = defaultdict(list)
-        revocations_parents_organizer = HierarchyOrganizer()
-
-        # print(f'*** process_revocations: {len(self.revoke_info)}')
+        revocated_relations_organizer = HierarchyOrganizer()
 
         # First, collect all revocations
         for model_name, items in self.revoke_info.items():
             revocations[model_name].extend(items)
-
-            # print(f'*** process_revocations for {model_name}')
+            logger.info(f'$$$ process_revocations for {model_name}, items = {len(items)}')
 
             # Process parent hierarchies for each revoked item
             model = model_registry.get_model(model_name)
             for item in items:
+
+                logger.info(f'$$$ item revoked = {item}')
+
                 try:
                     instance = model.objects.get(id=item['model_id'])
-                    # print(f'*** process revoked item parents of {model_name} : {item['model_id']}')
-                    add_parents_with_hierarchy_organizer(instance, revocations_parents_organizer)
+                    logger.info(f'$$$ process revoked item parents of {model_name} : {item['model_id']}')
+                    revocated_relations_organizer.add_relations(instance)
+
                 except model.DoesNotExist:
                     pass
 
-        return revocations, revocations_parents_organizer
+        children = revocated_relations_organizer.grouped_children()
+        merged_revocations = merge_dicts(revocations, children)
+
+        return merged_revocations, revocated_relations_organizer
 
     def get_response_data(self):
         """Construct the complete response data structure."""
         shared, grants = self.process_shared()
-        revocations, revocations_parents_organizer = self.process_revocations()
+        revocations, revocated_relations_organizer = self.process_revocations()
 
         # print(f'self.deletions = {dict(self.deletions)}')
         # print(f'self.shared_relationship_sets = {self.shared_relationship_sets}')
         # print(f'self.shared_relationship_removals = {self.shared_relationship_removals}')
 
+        # logger.info('--------------------- SYNC')
+
         return {
             "updates": dict(self.updates),
             "deletions": dict(self.deletions),
             "shared": dict(shared),
             "grants": dict(grants),
             "revocations": dict(revocations),
-            "revocation_parents": revocations_parents_organizer.get_organized_data(),
+            "revocated_relations": revocated_relations_organizer.get_organized_data(),
             "shared_relationship_sets": self.shared_relationship_sets,
             "shared_relationship_removals": self.shared_relationship_removals,
             "date": self.last_log_date
@@ -451,3 +483,12 @@ class DataAccessViewSet(viewsets.ModelViewSet):
         if self.request.user:
             return self.queryset.filter(Q(related_user=self.request.user) | Q(shared_with__in=[self.request.user]))
         return []
+
+def merge_dicts(dict1, dict2):
+    result = defaultdict(list)
+
+    for d in [dict1, dict2]:
+        for key, value in d.items():
+            result[key].extend(value)
+
+    return dict(result)
diff --git a/tournaments/models/event.py b/tournaments/models/event.py
index 6e446f4..229fa73 100644
--- a/tournaments/models/event.py
+++ b/tournaments/models/event.py
@@ -26,7 +26,7 @@ class Event(BaseModel):
     def save(self, *args, **kwargs):
         if self.creator:
             self.creator_full_name = self.creator.full_name()
-        super(Event, self).save(*args, **kwargs)
+        super().save(*args, **kwargs)
 
     def display_name(self):
         if self.club and self.club.name and self.name:
diff --git a/tournaments/models/match.py b/tournaments/models/match.py
index ede4e07..33cf642 100644
--- a/tournaments/models/match.py
+++ b/tournaments/models/match.py
@@ -1,7 +1,9 @@
 from django.db import models
-# from tournaments.models import group_stage
-from . import TournamentSubModel, Round, GroupStage, FederalMatchCategory
 from django.utils import timezone, formats
+from django.core.exceptions import ObjectDoesNotExist
+
+from . import TournamentSubModel, Round, GroupStage, FederalMatchCategory
+
 from datetime import datetime, timedelta
 
 import uuid
@@ -90,14 +92,16 @@ class Match(TournamentSubModel):
             return '--'
 
     def stage_name(self):
-        if self.name:
-            return self.name
-        elif self.round:
-            return self.round.name()
-        elif self.group_stage:
-            return self.group_stage.display_name()
-        else:
-            return '--'
+        try:
+            if self.name:
+                return self.name
+            elif self.round:
+                return self.round.name()
+            elif self.group_stage:
+                return self.group_stage.display_name()
+        except ObjectDoesNotExist:
+            pass
+        return "--"
 
     def get_previous_round(self):
         # Calculate the next index
diff --git a/tournaments/models/team_score.py b/tournaments/models/team_score.py
index 14765a6..b4845ff 100644
--- a/tournaments/models/team_score.py
+++ b/tournaments/models/team_score.py
@@ -1,4 +1,6 @@
 from django.db import models
+from django.core.exceptions import ObjectDoesNotExist
+
 from . import TournamentSubModel, Match, TeamRegistration, FederalMatchCategory
 import uuid
 from .match import Team  # Import Team only when needed
@@ -15,10 +17,14 @@ class TeamScore(TournamentSubModel):
         pass
 
     def __str__(self):
-        if self.match:
-            return f"{self.match.stage_name()} #{self.match.index}: {self.player_names()}"
-        else:
-            return "Empty"
+        try:
+            if self.match and self.team_registration:
+                return f"{self.match.stage_name()} #{self.match.index}: {self.player_names()}"
+            if self.match:
+                return f"{self.match.stage_name()} #{self.match.index}"
+        except ObjectDoesNotExist:
+            pass
+        return "--"
 
     def get_tournament(self): # mandatory method for TournamentSubModel
         if self.team_registration:
@@ -48,14 +54,16 @@ class TeamScore(TournamentSubModel):
     #         return None
 
     def player_names(self):
-        if self.team_registration:
-            if self.team_registration.name:
-                return self.team_registration.name
-            else:
-                names = self.team_registration.team_names()
-                return " - ".join(names)
-        else:
-            return "--"
+        try:
+            if self.team_registration: # this can cause an exception when deleted
+                if self.team_registration.name:
+                    return self.team_registration.name
+                else:
+                    names = self.team_registration.team_names()
+                    return " - ".join(names)
+        except TeamRegistration.DoesNotExist:
+            pass
+        return "--"
 
     def shortened_team_names(self, forced=False):
         names = []