You need to provide two forms of proof of residency to obtain this. 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).Those who don't have the required residency documents must complete an Arizona Residency Affidavit and supply additional proof of residency. US Passport or US Passport Card 2. These additional financial sponsors also have to submit an Affidavit of Support, proof of their income, and proof of their legal status in the United States. A declaration is a simple statement that you intend in good faith to return to the United States to resume your domicile.