I'm willing to bet you have no actual psychological training AT ALL. Wanna know how I know? Because MPD isn't called MPD anymore. It hasn't been FOR YEARS. It's called Disassociative Identity Disorder now. Wanna know how I know that? Because I've studied it extensively. I've written papers on it. I've read books, articles, and I've even diagnosed someone with it.
What you're doing with people is EXTREMELY DANGEROUS. Most people with DID don't have demons. I'm going to repeat myself. They do not have demons! And when you go about casting out alters it's damaging. What if you've decided to cast out a suicidal alter? It's not going to retreat, it's not going to integrate. That's not how it's done! You've now put the individual in a unhealthy and dangerous space. You've probably set them back years of health... and you know what's the worst? If they weren't aware of their alters, you've now brought them out. AND YOU CAN'T TREAT THEIR DID! What are they supposed to do now? When you bring alters forward, you bring memories and another personality. Do you have any idea what you've done to them?! Or do you not care?
How can you play this game with them? Did you hang a shingle or set up a tent? Are you selling snake oil too?