Why would you want to know about multiple personalities? It is a rare disorder to begin with, those who actually have it do not remember the other personalities typically, and generally those diagnosed with it are in hospital permanently or jail.
People try and fake having it, and those who do are very easily found because they try and reference the other personality. I had one person come here stating they had it, registered multiple usernames here, stating it was their different personalities. Under such circumstances multiple personalities would not do that to begin with, as one personality is very different to the other, even typically totally different lifestyle, attitude, everything. A person with multiple personalities would never be known here as you would only ever know one personality, being the one who has PTSD or believes they have PTSD. You would never know it here.
Multiple personalities is not PTSD related either, so its not a topic of discussion here. There are forums already that would exist for such issues.