Petition for (Custody) (Visitation). Where to File for Custody.Custody cases are usually started in Family Court. Complete General Form 17 to petition for custody or visitation. File for Child Custody. Below are links to commonly used probate forms. This file provides a template for filing a petition to modify custody and child support in Fulton County, Georgia. When you file a document with the Court: o Always include the full case name and file and petition numbers (if there are any).