I want to add myself as subscriber to all newly created Maniphest tasks if they belong to a certain project or any of its subprojects.

As far as I found out, what I have to do is to add a Herald rule

applies if ANY of existing projects <MAIN_PROJECT> <SUB_PROJECT1> <SUB_PROJECT2>

Probably something like this. However, this rule will miss all subprojects that are generated after I created this rule.

How could I solve this situation?