Supplemental Petition for Modification of Child Support. Form Number. 12.905(b).Below is a list of forms that you may download for free from our website. The purpose of this form is to notify the Department of Social Services of any significant changes in circumstances that may affect child support obligations. SUPPLEMENTAL PETITION FOR MODIFICATION OF CHILD SUPPORT​​ I, {full legal name} , being sworn, certify that the following information is true: 1. Court case number; Respondent's social security number; Name of the county where your support order originated i.e. This form should be used when you are asking the court to change a current court-ordered child support obligation. The big question is WHY are you wanting to reduce child support payments? Enter your zip code to see attorneys available in your area. However, we may not have opened a child support case.