Much confusion surrounds the need to submit I751 affidavits and how to write them. We explain and provide an I-751 affidavit sample.1. Complete the entire Affidavit in black ink. To complete this form you will need: ✓. A copy of your current child support order. ✓. This document provides a sample affidavit that friends or family can use to write a letter of support for a Form I-751 petition. Forms and information for filing for child support or requesting child support direct deposits in Arizona. This article provides a comprehensive sample of an affidavit letter, guiding readers through the essential components and format. Court Forms and Instructions. Completing the Forms.