I've read the book and saw the movie. "Sybil" was a pseudonym for Dr. Wilbur's patient to protect her real identity.
DID (or MPD) is an actual diagnosis from what I've heard. Some of those affected have been tested in their different personalities and there have been striking differences among them, up to and including different "native" languages, handwriting and IQ.
I don't know if Sybil was "created" or fabricated but there is one (who prefers to remain completely out of the spotlight) that was from the area I live and was treated in town. The book is The Minds of Billy Milligan (yes, that's his real name). Dr. Wilbur was peripherally involved in his case since she was the acknowledged "expert" in MPD. However, his case doesn't have the "happy ending" that Sybil's did. He was never fully integrated.
If you're interested in this kind of book, slhim, another one you may be interested in is called When Rabbit Screams. Also about an MPD patient but one who *chose* not to even try integration. It was written by The Troops For Trudy Chase (Yes that's the "author") and it gives and "inside" view of a MPD, written from their perspective.BH Cee64D - 48
WW (me) - 49
All affairs are variations on a theme. No one has 'Beethoven's 5th' to everyone else's 'Chopsticks'.