“My wife’s brother should be paying child support. However, his parents agreed to take the children and raise them in their home several years ago. They have now lived with the grandparents for the past four years. The brother’s wife is now asking for back child support during that period. Does the wife have the right to the child support since the kids have not lived with her?”

Orders are good when made. If you are entitled to a child support modification seek it immediately. When situations and agreements change, get it in a written Court order. If you sleep on your rights, you do so at your own peril.

He owes the support to someone. If not the ex (per the Court order) then to the grandparents. In determining an arrears amount, the Court may take into consideration the fact that the children did not actually reside with mother to give him an equitable reduction in the support amount owed to her. He will likely need an attorney to make this argument effectively. He should also pay all the back owed support to his parents while he is at it, and if they do not want it, put it into an account for the child to receive upon reaching majority.