You can file a petition for child custody in your county's Superior Court. If you are divorcing, the petition will be included in your divorce papers.Petition for (Custody) (Visitation). These forms and instructions are available in the General Clerk's Office, Room 108, in the Nassau County. These are documents and forms relating to the areas in which they are located. Most documents and forms on this website are in Adobe Acrobat (. Org - (select) – Self Help, Family Law Forms for the forms. 2.