There should be a way to select who are the Doms and who are the subs. Would make it easier to let your "slaves" gangbang you. Only place to do this is in the sewers, but the transformation part to remove the futa gets a little too tedious (I am not into it. I am into strapons instead). Also they are filithy imps.
It could be an easy update; let a slave set as "use you" to use you even if you have another slave in your party.
The thing is, Inno's no longer supporting companion content going forward. So anything that requires you to have a slave in your party isn't going to be a new feature.
A possibility of multiple slaves "using you" (if you have multiple slaves with that permission enabled) in the mansion sounds like a good idea though. Currently the only way to have your slaves spitroast you is to initiate subby-sex while two or more are present. So perhaps if there are multiple slaves with the "use you" permission enabled, there could be a chance (say, 25%) that they'll gang up on you.
Also*, you can enchant Mystery Kink potions to give specific fetishes (ie. Dominant, Sadistic and Non-Consent) while adding an aversion to certain acts. So equipping your MILF librarian, office manager or head chef with a strapon and giving her the Vaginal, Cock Stud and Anal fetishes (along with the aforementioned ones) while making her hate
receiving anal, oral and vaginal or
giving oral should create an NPC with an obsession for rogering the MC with a rubber dong.
Let us know how it works out.
* Many people posting here seem unaware that you can enchant consumables. Sorry if I'm explaining something you already know.