Usually psychotherapists prefer to develop a treatment "alone", disfavoring the intervention of another psychological therapist at the same time. But in complex cases with different problematics, the intervention of other experts may be useful, like in medicine (cardiac problems with cardiologists & self-immune with immunologists). For example, is a concurrent psychological treatment (different psychotherapists) advisable in cases of comorbidity of HIV, drug abuse, cognitive deterioration, personality disorder, psychosis, family conflicts, etc.?