My exhusband/biological father of my children has agreed in a court ordered mediation that he would sign over his parental rights and allow my husband( the only father the children want in their life) to adopt the children and I wouldn't come after him for back unpaid medical bills he still owes me since the divorce ranging in the 4-6K range. Now inorder for him to sign the papers he is now asking that I pay him back the childsupport he has been paying since the mediation agreement was made and sign a paper stating I would allow him to claim one of the children on his 2010 taxes which he would have no legal right to do since they have not visited,stayed over night,lived with him in the last 3 years. I am wondering if this would constitute as blackmail or extortion on his part and what can I do about it?