303.19—Parent.
        
        (3) 
         A person acting in the place of a parent (such as a grandparent or stepparent with whom the child lives, or a person who is legally responsible for the child's welfare); or
    
    
    
        
        (b) Foster parent.
         Unless State law prohibits a foster parent from acting as a parent, a State may allow a foster parent to act as a parent under Part C of the Act if—
    
    
        
        (1) 
         The natural parents' authority to make the decisions required of parents under the Act has been extinguished under State law; and