not making a diagnosis or anything but this sounds like this friend of yours may have more than one mental disorder.

heres why I am guessing that...

dissociative alters are not created out of the blue complete with a back story. and doesnt happen just because a celebrity dies and a person doesnt want to believe the celebrity is gone.

there is so much involved in the mechanics of the creation of alters associated with DID. it isnt a situation where a person wants to be friends with a celebrity and so they incorporate that celebrity into their mind with a back story. in fact the diagnostic criteria for america is that this kind of alter rules out having DID.

that said some people that I know do have alters that are dead celebrities. these people that I know have psychosis, psychotic type mental disorders and others just wanted to have an invisible friend.

my suggestion would be to contact your treatment providers they will be able to help you to understand the mechanics (how the brain works physically and mentally) and all the different elements that have to come together in order for a dissociative type alter with DID to be created. its things like brain waves, age of the child, type of abuse, the childs culture and many other things have to line up completely before an alter with DID is created.