Difficult situation. With regard to child support, I believe it is possible to petition for a reevaluation of the amount paid to her by her ex-husband. The attorney who handled her divorce can advise on this. Most decent attorneys will give a free consult before taking someone on as a client, if she thinks a new attorney would be a better match for her. Legal Aid is another resource. Also the office of the Friend of the Court in her district.

As for everything else, I doubt she has any standing. Once the settlement papers are signed, they're signed. At least that's my understanding.