This guide includes forms and instructions for a letter and affidavit to request that the court register an out-of-state custody order in Texas. Custodial Parent's Certification of Direct Payments.I understand I must fill out and attach a Declaration in Support of Changing. Primary Custody within One Year form to this Petition. File this form when you and the other party cannot agree to a temporary arrangement for parenting, child support, or other issues before the final hearing date. To open a child support case in Texas, you'll need to provide information about yourself and the other parent. These guides and articles can help you establish, modify, and enforce custody and visitation in Texas family court. Here's what to expect when you request for a modification of your child support order. Click here to learn the steps in the modification journey. Or click here to download, complete, and mail the "Request for Review" form to the Child Support Division.