I would expect my sub/slave to serve at my party you could have her as head slave or something and have the other subs take her orders if she wanted that kind of power but you are the Dom if anything goes wrong with the party its her butt on the line in more then one way

As for the ladies only party, why cant the Doms turn up have the subs trying on toys and cloths in front of a group of Doms and subs sounds like a lot more fun for the subs and the Doms