My question involves a person located in the state of: California

How does an international student, who already has his I-20 certification and his F1 Visa, apply for guardianship by a relative who lives in California?

The student is currently 18 years old and is enrolled at a private university. He will be renting a room from us in California and we want him to have legal guardianship with his uncle who lives in California because we don't want to be responsible or have liability issues.