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.You're always welcome to change the way you make your child support payments, but the court-ordered amount can change only through a court order. Step 1: Fill out your court forms. Fill out the following starting forms: â—‹ Petition to Modify the Parent-Child Relationship. If you would like to change a child support or custody order that resulted from a SAPCR, you will need to file with the court for a modification. The blue form anda court order is needed to modify an existing child support order and set up a new case. A parent who wishes to alter an order pertaining to child support must file a suit for modification in the county that issued the current order. In Texas, a child support agreement can be modified three years after it was put into place or last modified. How Do You Modify Child Support in Texas?