Section 4BB. Any subscription certificate under an individual or group medical service agreement, except certificates that provide stand-alone dental services, supplemental coverage to Medicare or other governmental programs, that is delivered or issued or renewed in the commonwealth, shall provide, as benefits to all individual subscribers and members within the commonwealth and to all group members having a principal place of employment within the commonwealth, coverage to eligible dependents under 26 years of age or without regard to age, so long as the dependent, who is covered under the membership of their parent as a member of a family group, is mentally or physically incapable of earning their own living due to disability.