Box 1: Print the county in which you are filing your petition. See "Where do I. File?" in the Introduction for more information about what county you.An overview of modifications to child support agreements and reasons that the court would consider them. Petition for Modification. Each of the documents listed below inculde a blank form and the instructions to fill out that form. How to fill out child support modification papers? Complete and attach this form to a complaint in a family case. You should be able to file online through Pennsylvania Child Support Enforcement System (PACSES) website. Sample Forms These sample forms may be useful when filing documents for the civil and family courts. If you have any questions, consult an attorney.