diff --git a/src/core/migrations/versions/9de844252cd5_osint_source_group_cascade_delete.py b/src/core/migrations/versions/9de844252cd5_osint_source_group_cascade_delete.py
new file mode 100644
index 00000000..098d613b
--- /dev/null
+++ b/src/core/migrations/versions/9de844252cd5_osint_source_group_cascade_delete.py
@@ -0,0 +1,45 @@
+"""add cascade delete/null to osint_source_group releated tables
+
+Revision ID: 9de844252cd5
+Revises: 90249a322ae1
+Create Date: 2024-10-18 14:13:00.653593
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '9de844252cd5'
+down_revision = '90249a322ae1'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    delete_previous()
+
+    # news_item_aggregate
+    op.create_foreign_key('news_item_aggregate_osint_source_group_id_fkey',             'news_item_aggregate',             'osint_source_group', ['osint_source_group_id'], ['id'], ondelete='SET NULL')
+    # remote_node
+    op.create_foreign_key('remote_node_osint_source_group_id_fkey',                     'remote_node',                     'osint_source_group', ['osint_source_group_id'], ['id'], ondelete='SET NULL')
+    # news_item
+    op.create_foreign_key('osint_source_group_osint_source_osint_source_group_id_fkey', 'osint_source_group_osint_source', 'osint_source_group', ['osint_source_group_id'], ['id'], ondelete='CASCADE')
+
+def downgrade():
+    delete_previous()
+    # news_item_aggregate
+    op.create_foreign_key('news_item_aggregate_osint_source_group_id_fkey',             'news_item_aggregate',             'osint_source_group', ['osint_source_group_id'], ['id'])
+    # remote_node
+    op.create_foreign_key('remote_node_osint_source_group_id_fkey',                     'remote_node',                     'osint_source_group', ['osint_source_group_id'], ['id'])
+    # news_item
+    op.create_foreign_key('osint_source_group_osint_source_osint_source_group_id_fkey', 'osint_source_group_osint_source', 'osint_source_group', ['osint_source_group_id'], ['id'])
+
+def delete_previous():
+    print("deleting previous objects...", flush=True)
+    # news_item_aggregate
+    op.drop_constraint('news_item_aggregate_osint_source_group_id_fkey',             'news_item_aggregate', type_='foreignkey')
+    # remote_node
+    op.drop_constraint('remote_node_osint_source_group_id_fkey',                     'remote_node',         type_='foreignkey')
+    # news_item
+    op.drop_constraint('osint_source_group_osint_source_osint_source_group_id_fkey', 'osint_source_group_osint_source', type_='foreignkey')
diff --git a/src/core/model/news_item.py b/src/core/model/news_item.py
index 3535ec7c..c56d7f0f 100644
--- a/src/core/model/news_item.py
+++ b/src/core/model/news_item.py
@@ -941,13 +941,14 @@ def update_status(cls, aggregate_id):
     @classmethod
     def get_news_items_aggregate(cls, source_group, limit):
         limit = datetime.strptime(limit['limit'], '%d.%m.%Y - %H:%M')
-
-        # TODO: Change condition in query to >
-        news_item_aggregates = cls.query.filter(cls.osint_source_group_id == source_group).filter(cls.created > limit). \
-            all()
+        news_item_aggregates = cls.query.filter(cls.osint_source_group_id == source_group).filter(cls.created > limit).all()
         news_item_aggregate_schema = NewsItemAggregateSchema(many=True)
         return news_item_aggregate_schema.dumps(news_item_aggregates)
 
+    @classmethod
+    def get_news_items_aggregate_by_source_group(cls, source_group_id):
+        return cls.query.filter(cls.osint_source_group_id == source_group_id).all()
+
 
 class NewsItemAggregateSearchIndex(db.Model):
     id = db.Column(db.Integer, primary_key=True)
diff --git a/src/core/model/osint_source.py b/src/core/model/osint_source.py
index bf0fe374..8d580e12 100644
--- a/src/core/model/osint_source.py
+++ b/src/core/model/osint_source.py
@@ -347,10 +347,19 @@ def add(cls, data):
 
     @classmethod
     def delete(cls, osint_source_group_id):
+        from model.news_item import NewsItemAggregate # must be here, because circular import error
+
         osint_source_group = cls.query.get(osint_source_group_id)
         if osint_source_group.default is False:
             db.session.delete(osint_source_group)
             db.session.commit()
+            # Checking multiple source group assignments is problematic due to the existence of more NewsItemsAggregate records
+            # and the source assignment may change over time. Let's move them to the default group.
+            default_group = cls.get_default()
+            newsItemAggregates = NewsItemAggregate.get_news_items_aggregate_by_source_group(None) # we use db delete rule: set null
+            for item in newsItemAggregates:
+                item.osint_source_group_id = default_group.id
+            db.session.commit()
             return "", 200
         else:
             return {'message': 'could_not_delete_default_group'}, 400