diff --git a/kfet/migrations/0066_on_delete_actions.py b/kfet/migrations/0066_on_delete_actions.py
index 157e1247..e2d635e2 100644
--- a/kfet/migrations/0066_on_delete_actions.py
+++ b/kfet/migrations/0066_on_delete_actions.py
@@ -29,18 +29,6 @@ class Migration(migrations.Migration):
                 to="kfet.Checkout",
             ),
         ),
-        migrations.AlterField(
-            model_name="inventory",
-            name="order",
-            field=models.OneToOneField(
-                blank=True,
-                default=None,
-                null=True,
-                on_delete=django.db.models.deletion.CASCADE,
-                related_name="inventory",
-                to="kfet.Order",
-            ),
-        ),
         migrations.AlterField(
             model_name="inventoryarticle",
             name="article",
@@ -67,18 +55,6 @@ class Migration(migrations.Migration):
                 to="kfet.Article",
             ),
         ),
-        migrations.AlterField(
-            model_name="operationgroup",
-            name="valid_by",
-            field=models.ForeignKey(
-                blank=True,
-                default=None,
-                null=True,
-                on_delete=django.db.models.deletion.SET_NULL,
-                related_name="+",
-                to="kfet.Account",
-            ),
-        ),
         migrations.AlterField(
             model_name="order",
             name="supplier",
@@ -116,18 +92,6 @@ class Migration(migrations.Migration):
                 on_delete=django.db.models.deletion.CASCADE, to="kfet.Supplier"
             ),
         ),
-        migrations.AlterField(
-            model_name="transfergroup",
-            name="valid_by",
-            field=models.ForeignKey(
-                blank=True,
-                default=None,
-                null=True,
-                on_delete=django.db.models.deletion.SET_NULL,
-                related_name="+",
-                to="kfet.Account",
-            ),
-        ),
         migrations.DeleteModel(name="ArticleRule"),
         migrations.DeleteModel(name="CheckoutTransfer"),
     ]
diff --git a/kfet/migrations/0068_on_delete_account.py b/kfet/migrations/0068_on_delete_account.py
index 8bb79af6..b8cfdb76 100644
--- a/kfet/migrations/0068_on_delete_account.py
+++ b/kfet/migrations/0068_on_delete_account.py
@@ -70,6 +70,18 @@ class Migration(migrations.Migration):
                 to="kfet.Account",
             ),
         ),
+        migrations.AlterField(
+            model_name="operationgroup",
+            name="valid_by",
+            field=models.ForeignKey(
+                blank=True,
+                default=None,
+                null=True,
+                on_delete=models.SET(kfet.models.get_deleted_account),
+                related_name="+",
+                to="kfet.Account",
+            ),
+        ),
         migrations.AlterField(
             model_name="transfer",
             name="canceled_by",
@@ -100,4 +112,16 @@ class Migration(migrations.Migration):
                 to="kfet.Account",
             ),
         ),
+        migrations.AlterField(
+            model_name="transfergroup",
+            name="valid_by",
+            field=models.ForeignKey(
+                blank=True,
+                default=None,
+                null=True,
+                on_delete=models.SET(kfet.models.get_deleted_account),
+                related_name="+",
+                to="kfet.Account",
+            ),
+        ),
     ]
diff --git a/kfet/models.py b/kfet/models.py
index 719a3b0d..5d8ad3cb 100644
--- a/kfet/models.py
+++ b/kfet/models.py
@@ -530,7 +530,7 @@ class Inventory(models.Model):
     # Optional
     order = models.OneToOneField(
         "Order",
-        on_delete=models.CASCADE,
+        on_delete=models.PROTECT,
         related_name="inventory",
         blank=True,
         null=True,
@@ -618,7 +618,7 @@ class TransferGroup(models.Model):
     comment = models.CharField(max_length=255, blank=True, default="")
     valid_by = models.ForeignKey(
         Account,
-        on_delete=models.SET_NULL,
+        on_delete=models.SET(get_deleted_account),
         related_name="+",
         blank=True,
         null=True,
@@ -668,7 +668,7 @@ class OperationGroup(models.Model):
     comment = models.CharField(max_length=255, blank=True, default="")
     valid_by = models.ForeignKey(
         Account,
-        on_delete=models.SET_NULL,
+        on_delete=models.SET(get_deleted_account),
         related_name="+",
         blank=True,
         null=True,