hi,

I wondered the same as Lizardlady asked earlier

If you mean dissociative identity disorder some of your question is addressed in this article
What is a dissociative disorder which also explains the connection between your question and why the name was changed from multiple personality disorder to dissociative identity disorder
there are also links to other resources on Psych Central that you may like to explore - these can be found here - Psych Central: Dissociation