Child Support Forms ; 4-3b. Addendum to Support Petition– Request for Child Support (IV-D) Services.1. Fill out a child support modification petition. 2. File the petition with the Family Court that most recently established your order. A custodial parent can waive or forgive all arrears owed to him or her directly. These are the official forms for use in Family Court proceedings. Use our printable child support demand letter template to require someone to pay their owed child support. Download it for free here. Learn how to complete a Statement of Arrears form or claim interest on unpaid support. 4-3b. Addendum to Support Petition– Request for Child Support (IV-D) Services.