Covered treatment for a minor includes treatment for the family if family therapy is recommended by a health maintenance organization provider. For purposes of determining benefits under this section, “hours of treatment” means treatment rendered on an individual or single-family basis. If treatment is rendered on a group basis, the hours of covered group treatment must be provided at a ratio of no less than two group treatment sessions to one individual treatment hour. For a health maintenance contract that is offered as a companion to a health insurance subscriber contract, the benefits for mental or nervous disorders must be calculated in aggregate for the health maintenance contract and the health insurance subscriber contract.