This kills me too. When I get a request and mine is full, sometimes I just click the circle that says “savvy” or whatever and click on the first person (lowest level) to clear a spot quickly in a party when I really want to add someone. Otherwise, I do the active day thing.
The 10 party thing is a steep marker though and a great idea!
My problem is I can’t tell which friends are connected to Sims I am actively “in a relationship” story with so I don’t know if my criteria removes them. But I guess it really doesn’t matter since I can’t chat with them about their Sim’s story anyway!