No contract or evidence of coverage issued by a Health Maintenance Organization which provides for coverage of dependents of the principal enrollees shall exclude a child from coverage or eligibility for coverage or limit coverage for a child solely on the basis that he or she is an adopted child. For purposes of this Section, a child who is in the custody of a principal enrollee, pursuant to an interim court order of adoption or, in the case of group insurance, placement of adoption, whichever comes first, vesting temporary care of the child in the enrollee, is an adopted child, regardless of whether a final order granting adoption is ultimately issued.