How can my mom and dad get custody of my 3 year old cousin?

My mom and dad want custody of my cousin Cam. He's three and was taken from his dad less then a year age because he beet him. His mother also lost custody because of her drug use. Cam was given to his grandmother in emergency custody. They live in Taxes all of his life till about a month ago when she moved to California, to get him away from them. We fell in love with the boy and for two weeks now he's lived with my parents. They tried to state the adoption when this morning Cam's dad show up at our door with a court order from Oklahoma to take him. Is there anyway to get him back?