You can not have her come home after the party. Tell her you'd like to treat her and her girlfriend to an overnight hotel stay. Be as frank, as you feel you can be, with the girl friend and infer, if not flat out tell her that it would great with you if the wife got fucked or played with.Now the girlfriend will not fear that she will be blamed for any indiscretions, but rather will be emboldened to get the wife primed for a great night.Needless to say, the girlfriends needs to know that text and pic are greatly appreciated.