This guide includes forms and instructions for a letter and affidavit to request that the court register an out-of-state custody order in Texas. I understand I must fill out and attach a Declaration in Support of Changing.Primary Custody within One Year form to this Petition. This chapter of the Texas Family Code describes who can file a SAPCR, how they must do so, and what the petition must contain. Texas Family Code, Chapter 103. The following forms are available for downloading, printing and completing. These forms and instructions are available in the General Clerk's Office, Room 108, in the Nassau County.