Want to find an experienced lawyer in reversing guardianship for my veteran brother who's got mental health issues who's niece has taken that role.

I am the sister who visited my brother in Phoenix recently and found him living in very unhealthy conditions with my niece living with him for4 years and not giving him the proper care and now she has gone to court to become guardian so that she can have control over his finances and who can visit etc. He has a son who would like to care for his father but my niece won't allow him to move there. She is trying to isolate my brother and have him sign his house over to her which she feels she deserves. My question is if his son can have an attorney assist him in reversing guardianship and appointing him as his father's guardian. I don't think my niece is the best choice for my brother's caretaker. Thank you for your time.. Cynthia