James A. Chu said this quote

Switches among identities occur in response to changes in emotional state or to environmental demands, resulting in another identity emerging to assume control. Because different identities have different roles, experiences, emotions, memories, and beliefs, the therapist is constantly contending with their competing points of view. Helping the identities to be aware of one another as legitimate parts of the self and to negotiate and resolve their conflicts is at the very core of the therapeutic process. It is countertherapeutic for the therapist to treat any alternate identity as if it were more “real” or more important than any other.Guidelines for Treating Dissociative Identity Disorder in Adults, Third Revision

~ James A. Chu

The primary treatment modality for DID is individual outpatient psychotherapy.Guidelines for Treating Dissociative Identity Disorder in Adults, Third Revision

~ James A. Chu

Treatment for DID should adhere to the basic principles of psychotherapy and psychiatric medical management, and therapists should use specialized techniques only as needed to address specific dissociative symptomatology.Guidelines for Treating Dissociative Identity Disorder in Adults, Third Revision

~ James A. Chu

The DID patient is a single person who experiences himself or herself as having separate alternate identities that have relative psychological autonomy from one another. At various times, these subjective identities may take executive control of the person’s body and behavior and/or influence his or her experience and behavior from “within.” Taken together, all of the alternate identities make up the identity or personality of the human being with DID.- Guidelines for Treating Dissociative Identity Disorder in Adults, Third Revision, p7

~ James A. Chu