child is 14 years old. Her stepfather file for her mom. Stepfather is a citizen. They came to US on visitor visa.. Change their status

The child does not obtain automatic US citizenship. A US citizen stepfather can sponsor his wife and his step child provided that both entered the United States with permission and the marriage occurred before the step child's 18th birthday. You sponsor both of them by filing an adjustment application to get their green cards. Once their green cards have been obtained, they can file for US citizenship three years later.