I believe your ex would be legally required to report this as a change of income for child support. I donu2019t know the child support regulations, but Iu2019m sure there are steps you can take if there was a change of income that your ex is not reporting. You can also request a modification of the child support agreement.The disability check should go to the parent who has custody. If you have custody, you can contact SSA and ask to be switched to be the childu2019s representative payee, and show proof you have primary custody.If it is joint custody, the decision about who is representative payee is usually part of the custody agreement. If it wasnu2019t you may need to go back through the courts and let a judge decide which parent is representative payee.