For her to be diagnosed with schizophrenia there would have to be more symptoms than hallucinations. Hallucinations and delusions are possible sign of psychosis, and therefore schizophrenia, but there are many other symptoms of schizophrenia. Other symptoms of schizophrenia include anger outbursts, neglecting personal hygiene, hearing voices, trouble attending school or work, diminished emotions, social withdrawal, and others. These symptoms, according to the DSM-IV-TR, the manual used by mental health professionals to diagnose disorders, must be present for at least one month.
I’m curious about what you mean by the term hallucination. If I had the opportunity to interview you I would want you to explain this in more detail. Some people confuse the terms hallucination and delusion and it would be helpful to know more about what your friend is experiencing.
It is difficult to answer your question about whether it is problematic that you and your friend enjoy interacting with the child personalities. The answer depends on whether it harms her psychologically. Is it difficult for her to bring out these other personalities? Does she suffer as a result? Is this part of her treatment and is she in treatment? Is this is a technique designed by a therapist trained to treat dissociative identity disorder or is it something she began doing on her own? Knowing the answers to these questions would help me better answer your question.
The goal of treatment for dissociative identity disorder ultimately is integration. This process can take years. If the goal of treatment is integration then the fact that she is currently not integrated may be problematic. Perhaps she is unable to achieve the goal of integration at this juncture because she enjoys the presence of the other personalities. In this instance, having the other personalities present is possibly psychologically detrimental. Again, I am not certain of the specifics in this situation and therefore it’s difficult to give a definitive answer.
Generally speaking, if she is having hallucinations this is not healthy. If she is not already in treatment please encourage her to see a mental health professional who specializes in dissociative identity disorder. Treatment does not mean she has to abandon her personalities but it may help her to manage them in a psychologically beneficial way. Remember, the personalities are present because they are concealing a painful reality. Eventually, for her to fully recover, she will have to address that painful reality. This is a complicated process that requires the assistance of a competent mental health professional.
I hope this helps answer some of your questions. I wish you and your friend the best of luck.