Qualified Medical Child Support Order. The name and address of the other parent.1. Fill out a child support modification petition. 2. File the petition with the Family Court that most recently established your order. This document is a sample form letter designed for individuals seeking a downward modification of their child support obligations. To file such a motion, you generally need to explain the change in circumstances that have taken place which warrant changing the current support order. Download a free child support modification form to propose changes to a current child support agreement. Available in PDF or Word format. I do not agree with this. I want partial physical and legal custody of my child.