Qualified Medical Child Support Order. 1. Fill out a child support modification petition. 2.File the petition with the Family Court that most recently established your order. 3. 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. These forms and instructions are available in the General Clerk's Office, Room 108, in the Nassau County. Either party may contact the DRO and request child support services. You may also complete an Application for Child Support Services available on this website. How do I fill this out? IV-D Child Support Courts are located in the Family Law Center at 1115 Congress, Houston, TX 77002.