This woman may have fallen on hard times applied for assistance and they require you to cooperate in order to receive funding for usually welfare. She probably didn't think they would really find you. She may not have even given your address they may have just found you through your social security number. Or she could have given your address in hopes of getting a large sum of money. You are probably going to have to pay up because you knew the order existed but you have to find out what state has juristiction over the case probably the one that granted the order in the first place, then file on violation of the parenting plan and for a modification of cs becuase after 10 years the amount should be different unless your making the same as you did back then. There might be some type of amnisty since you did not know were to find her to send a check. Depending on the judge and state laws you could have to pay anything from a portion of it to the whole thing or just pick up paying the new amount now. I suggest you go get another copy of the order from where it was granted and contact a lawyer to see how to proceed.