Hey thanks SlamPow!
I actually didn't give it too much thought. I hope guys with bigger brains can come up with some system that would be awesome!
As I see it when anyone joins a host he starts to share the hosts quests. For example if you already finished the Act 1 and Vometia is still wandering around the starting area (a beach btw!) with her trousers! (see pants) on her head!! (no pants below) (it stuck in my "imagine this" section of the brain). Ok so, we share her quests, if lets say she plays as a Lohse and you would want to joint her as a Lohse too, we will get a blue screen of death and CTD. Well sh** I have no idea how to counter this.