If you have a joint sponsor, they must also complete Form I864. Use this form to show they have adequate means of financial support and are not likely to rely on the US government for financial support.You, the sponsor (petitioner), and the joint sponsor must complete Form I-864. See tips for completing Form I-864. 29. Enter the total number of immigrants you are sponsoring on this affidavit which includes the principal immigrant listed in Part 2. In today's video we are going to be filling out form i 864 the affidavit of support form for the joint sponsor. Someone who wants to sponsor a prospective immigrant to Atlanta must first complete and sign Form I-864, often referred to as an "affidavit of support." Some sponsors temporarily reside abroad and intend to move to the US once a family member's immigrant visa is issued. I am providing proof of the said funds to support this affidavit. In every scenario, a sponsor would have to file Form I864, Affidavit of Support.