In this section, “child dependent of the domestic partner” means an individual who: is: the natural child, stepchild, adopted child, or grandchild of the domestic partner of an insured; a child placed with the domestic partner of an insured for legal adoption; or a child who is under testamentary or court appointed guardianship, other than temporary guardianship of less than 12 months’ duration, of the domestic partner of an insured; is a dependent, as that term is used in 26 U.S.C. §§ 104, 105, and 106, and any regulations adopted under those sections, of the domestic partner of an insured; resides with the insured; is unmarried; and is under the age of 25 years. This section applies to each individual or group policy or contract that: allows family coverage; and is issued by: an insurer or nonprofit health service plan that provides inpatient hospital, medical, or surgical benefits to individuals or groups on an expense–incurred basis under health insurance policies or contracts that are issued or delivered in the State; or a health maintenance organization that provides inpatient hospital, medical, or surgical benefits to individuals or groups under contracts that are issued or delivered in the State. Each policy or contract subject to this section shall provide that the same health insurance benefits and eligibility guidelines that apply to any covered dependent are available to a domestic partner of an insured or a child dependent of the domestic partner of an insured at the request of: an insured under an individual policy or contract that is subject to this section; or the group policyholder of a group policy or contract that is subject to this section. An insurer, nonprofit health service plan, or health maintenance organization may require a group policyholder that requests coverage for a domestic partner or child dependent of the domestic partner of an insured under subsection (c)(2) of this section to provide proof of the eligibility of the domestic partner or child dependent of the domestic partner for coverage under this section. The Commissioner shall adopt regulations to implement this section.