So far, this game is really good, and the (minor) changes to the discussion with the dom or sub points are a real plus.
The possibility of adding other men to the game is tricky, especially considering that there aren't any so far, and adding them late could be disappointing for those already playing. Personally, as long as he doesn't penetrate any of the women, I'm not against it. Adding a cuckold (optional for the more oppositional) could be a good option.
Now, if it's to add penetration, adding strap-ons to one or more female characters should be fine (given that lesbian exchanges are already widely included in the game).