A. Your son’s stepmother can petition for a green card for him. Since your son came here legally, he can file his application for permanent residence together with a family petition signed by his stepmother. His stepmother must sign a completed U.S. Citizenship and Immigration Services form I-130, Petition for Alien Relative along with USCIS form I-864, Affidavit of Support. Your son files those forms with USCIS form I-485, Application to Adjust Status. He sends the package to USCIS, P.O. Box 805887, Chicago, IL 60680-4120.