Can someone W/Schizophrenia & Psychosis

Can someone with Schizophrenia & Psychosis also have Dissociative Disorder. My son is Schizophrenic with episodes of Psychosis. He has had visual and audio hallucinations since he was 3. I know it frighten him and we used to put music on at night to help him go to sleep. This way he couldn't hear the voices. The voices frighten him. I was afraid his doctor would put him on anti psychotic drugs so I didn't tell the doc. This was in the 80s when doctors were giving adult meds to children like candy. Any way my son managed well through his childhood years. When he turned 14 he started to have mood swings and issues with maintaining friendships with his peers. He always got along with the girls however. Over the years I have noticed he has distinct personalities that come and go. My son even refers to himself as us. A part of him is aware of the different selves but most selves don't know about each other. He has one part that hates me for things I did in another life, he has one who is young and loves me and is very kind to me. He has a dad part that came out when his sons were born. That part is irritated by me but is kind to me. And there are several other parts. I can see and identify five parts. I know how he will be toward to me depending who is out. The doctors said my son is Schizophrenic, bipolar with episodes of psychosis and delusion. He has these things. My question is can children who are experiencing visual and audio hallucinations at a very young age create selves to protect them from the fear? I have asked counselors and therapists but they are not familiar with DID and don't have an answer. I have even written to doctors who have written and studied DID and still have not heard back. I am at a loss to who to ask next. Any information would help. Thanks. Sorry for the long post.