Forms. Forms. Law Book Probate. Complete Sponsor's Personal Information Fill in the sponsor's full name, date of birth, and contact information.Complete the entire form. You may attach additional sheets if necessary, but do not simply state. Petitioner: The petitioner must complete an Affidavit of Support Form I-864. The person who signs the Affidavit of Support is also called the "sponsor. Use form when you file lawsuit, need affidavit regarding the other party's military status. CitizenPath has prepared a downloadable I751 affidavit sample that you can forward to friends who are willing to write a letter of support. Petitioner: The petitioner must complete an Affidavit of Support Form I-864. The person who signs the Affidavit of Support is also called the "sponsor.