If you want to sponsor someone for a family-based green card, you need to provide proof of a U.S. domicile in your Affidavit of Support (Form I-864). On Form I864, petitioners must prove that they have the ability to financially support the visa applicant(s) if necessary.My husband and I recently submitted the document to the NVC. His father is our joint sponsor to meet the requirements for the income. In today's video we are going to be filling out form i 864 the affidavit of support form for the joint sponsor.