diff --git a/fractal_database_matrix/controllers/replicate.py b/fractal_database_matrix/controllers/replicate.py
index daf07c1..cd5bff4 100644
--- a/fractal_database_matrix/controllers/replicate.py
+++ b/fractal_database_matrix/controllers/replicate.py
@@ -49,6 +49,8 @@ def to(
 
         try:
             homeserver = MatrixHomeserver.objects.get(url=homeserver_url)
+            if not homeserver.replication_enabled:
+                homeserver.update(replication_enabled=True)
         except MatrixHomeserver.DoesNotExist:
             with transaction.atomic():
                 # create the homeserver
@@ -58,6 +60,7 @@ def to(
                     type=MatrixHomeserver.__name__,
                     registration_token=registration_token,
                     parent_db=current_database,
+                    replication_enabled=True,
                 )
                 current_device.add_membership(homeserver)
         else:
diff --git a/fractal_database_matrix/migrations/0001_initial.py b/fractal_database_matrix/migrations/0001_initial.py
index 9dc6eca..71e9b12 100644
--- a/fractal_database_matrix/migrations/0001_initial.py
+++ b/fractal_database_matrix/migrations/0001_initial.py
@@ -19,6 +19,7 @@ class Migration(migrations.Migration):
                 ('url', models.URLField(unique=True)),
                 ('priority', models.PositiveIntegerField(blank=True, default=0, null=True)),
                 ('registration_token', models.CharField(blank=True, max_length=255, null=True)),
+                ('replication_enabled', models.BooleanField(default=False)),
             ],
             options={
                 'abstract': False,
@@ -35,7 +36,7 @@ class Migration(migrations.Migration):
                 ('matrix_id', models.CharField(max_length=255)),
                 ('password', models.CharField(blank=True, max_length=255, null=True)),
                 ('access_token', models.CharField(max_length=255)),
-                ('device', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='fractal_database.device')),
+                ('device', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, to='fractal_database.device')),
                 ('homeserver', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='credentials', to='fractal_database_matrix.matrixhomeserver')),
             ],
             options={
diff --git a/fractal_database_matrix/models.py b/fractal_database_matrix/models.py
index 4cd5ad4..2a6e11c 100644
--- a/fractal_database_matrix/models.py
+++ b/fractal_database_matrix/models.py
@@ -49,6 +49,7 @@ class MatrixHomeserver(Service):
     url = models.URLField(unique=True)
     priority = models.PositiveIntegerField(default=0, blank=True, null=True)
     registration_token = models.CharField(max_length=255, blank=True, null=True)
+    replication_enabled = models.BooleanField(default=False)
 
     def __str__(self) -> str:
         return f"{self.url} (MatrixHomeserver)"
@@ -205,7 +206,7 @@ class MatrixCredentials(BaseModel):
     homeserver = models.ForeignKey(
         MatrixHomeserver, on_delete=models.CASCADE, related_name="credentials"
     )
-    device = models.ForeignKey(Device, on_delete=models.CASCADE)
+    device = models.ForeignKey(Device, on_delete=models.CASCADE, blank=True, null=True)
 
 
 class InMemoryMatrixCredentials(MatrixCredentials):
diff --git a/fractal_database_matrix/signals.py b/fractal_database_matrix/signals.py
index 0b24bc6..f1caf61 100644
--- a/fractal_database_matrix/signals.py
+++ b/fractal_database_matrix/signals.py
@@ -26,7 +26,8 @@ def create_replication_channel_for_new_matrix_homeserver(
 
     if not created or raw:
         return
-
+    if not instance.replication_enabled:
+        return
     if not transaction.get_connection().in_atomic_block:
         raise Exception("Not in transaction")
 
@@ -83,6 +84,8 @@ def create_matrix_replication_target_for_new_database(
         return
 
     for homeserver in homeservers:
+        if not homeserver.replication_enabled:
+            continue
         instance.create_channel(
             MatrixReplicationChannel,
             homeserver=homeserver,