Once completed, note the SST number and come into our office to finish the process. Affidavit for marriage.Please print and complete this form. For completed examples of some legal forms, see our Self Help Form and Sample Packets page. Handwritten forms are hard to read. Enter: 3rd party relationship affidavits. This is where you ask friends or family members to write a sworn affidavit about the purported relationship. This letter confirms the genuine marriage of two friends who have been married for several years.