Maybe you create a custom relation, different from the “get_related_list” function, in your module and wants to set this relation also by the Workflow Designer.
If you already added the relation, you know, every relation especially the relations with custom queries, are not able to handle in a similar way.

That’s why I add one interface to add custom relations to Workflow Designer in an upgrade safe way.

Add a file “<filename>.inc.php” to the folder modules/Workflow2/extends/relation_add/
The file mostly is not very big and must have the following structure:

[prism language=php field=file]

You only need to set a UniqueRelationName, which is not related to the configured relation in vtiger, and add your custom code to add the relation in database.