Welcome to the Asana Community Forum @Charles_Cushman1!
Since rules don’t work on subtasks you won’t be able to multi-home the subtasks either so what you mentioned won’t really work. Unless you add the subtasks itself to the project too. You might be able to set something up if you have them as tasks instead, not subtasks.
In case you haven’t already you might want to upvote here: Allow Rules for Subtasks
Alternatively you can use Flowsana to set up rules for subtasks