Ultimately, the person who can make a final decision is the judge. So it sounds like what you're looking for is a qualified, neutral third-party who can evaluate your son and make a recommendation that influences that final decision.
That person could be a clinical psychologist, but it would necessitate several sessions and building a relationship with your DS and an understanding of the family dynamics before they would be qualified to answer.
Have you considered any resources available to your DS now, who have already developed a working relationship with him, as potential advisors? Current teachers, counselors, school psychologists? I would start my search there.
