My girlfriend has muliply personality disorder, and i have witnessed a lot of strage, weird stuff I have talked to 4 of these personalites all, different, my question is what are my do's and dont's with these other personalites?
It depends on the personalities, if they are good for her or if they are destructive. Encourage the healtiest of these personalities.
You and your girlfriend should discuss this with a psychiatrist. Hopefully she will pick up the best of the personalities in the long run and stay there.