Your brother is apparently sufficiently satisfied with his attorney since they have kept his representation. That attorney is guiding your brother and will answer your brother's questions including his options. You have no apparent standing to be involved in the matter, but may wish to speak with your brother to be better informed.
If you found this "helpful" or "best answer," please click it with my appreciation. My response is for educational purposes and does not constitute legal advice nor creates an attorney client relationship which requires all the details and a personal conference.
I agree, you have no standing to intervene in this matter. At a contested adoption trial, one hopes the truth will come out, although I assume there is more to this. If money is the thing keeping your brother from changing attorneys, perhaps you can help him in that way.
To questioners from West Virginia & New York: Although I am licensed to practice in your state, I practice on a day-to-day basis in Massachusetts. I answer questions in your state in areas of the law in which I practice, and in which I feel comfortable trying to offer you assistance based on my knowledge of specific statutes in your state and/or general principles applicable in all states. It is always best, however, to work with attorneys and court personnel in your own area to deal with specific problems and factual situations.