These forms and instructions are available in the General Clerk's Office, Room 108, in the Nassau County. 1. Fill out a child support modification petition. 2.File the petition with the Family Court that most recently established your order. 3. The Law Department assists local and out-of-state custodial parents in establishing an order of support from non-custodial parents. I do not wish to apply for child support services. â–¡ I am not eligible to apply for child support services because I am petitioning for spousal support only. 8. This program guides you step-by-step through court forms on any computer or mobile device. Answer a few simple questions and receive a completed PDF document. In New York State, a married person may file a petition in Family Court seeking spousal support from a current husband or wife. Phone: 718-990-1865.