diff --git a/app/Model/TaskDuplicationModel.php b/app/Model/TaskDuplicationModel.php
index eb59f5550..2076d0d43 100644
--- a/app/Model/TaskDuplicationModel.php
+++ b/app/Model/TaskDuplicationModel.php
@@ -36,6 +36,9 @@ class TaskDuplicationModel extends Base
         'recurrence_factor',
         'recurrence_timeframe',
         'recurrence_basedate',
+        'external_provider',
+        'external_uri',
+        'reference',
     );
 
     /**