(a) A custodial parent of a minor child, pursuant to an authorization to consent to health care for minor, may grant an agent full power and authority to consent to and authorize health care for the minor child to the same extent that a custodial parent could give such consent and authorization.
(b) An authorization to consent to health care for minor may contain, and the authority of the agent designated shall be subject to, any specific limitations or restrictions as the custodial parent deems appropriate.
(c) A custodial parent may not, pursuant to an authorization to consent to health care for minor, authorize an agent to consent to the withholding or withdrawal of life sustaining procedures.