"Multiple Personality is what it was called but that label is a misnomer. Split Personality is more accurate given that it describes what happens. A person does not receive a second personality from thin air. Instead the personality that the person does have splits into two or more partial personalities."
I wouldn't say that. The vast majority of mental health professionals never see anyone with this disorder... and in fact some don't agree that the disorder is involuntary. BUT, for the "believers," I've never seen the distinction described the way you described it. The diagnostic criteria require that each personality is a fully integrated and complex unit with memories, behavior patterns and social friendships.

"These partial personalities (if put together) equal one complete personality." While that may be one way to view the goal of treatment, (resolving and merging the "alters") it isn't a universally accepted concept among treating practitioners. But we could write a book about this (oops... others have), and never get high levels of agreement. This is a fairly good summary article which I belive was part of a doctoral dissertation: http://files.eric.ed.gov/fulltext/ED501858.pdf but alas, things have changed even since this was written in 2007. The changes have been (IMHO) political - in the highly controversial restructuring of the concepts and definitions of personality disorder by the American Psychiatric Association; not empirical...

And I apologize for semi-hijacking the tread: this diverges or dissociates from Jeanette's original post.... sorry.