Available DIY Forms ; Guardianship. This FSBO paperwork is needed as soon as you accept an offer, so it's useful to have a purchase agreement onhand that you can fill out quickly.New York requires those selling FSBO to fill out and file many documents and forms. Several of these documents are legally binding agreements. These forms are the legal documents the buyer and seller sign, putting the buyer's offer in writing and completing the transaction. Selling your home FSBO? 3. Describe the real estate. Provide the common address and the full legal description of the property. A One Time Showing Agreement is a commission agreement signed between a buyer's agent and a seller for specific named buyers. These are the official forms for use in Family Court proceedings.