(3) It purports to insure only 1 person, except that a policy, excluding contracts which provide stand-alone dental services, shall insure, originally or by subsequent amendment, upon the application of an adult member of a family who shall be considered the policyholder, 2 or more eligible members of that family, including the policyholder, spouse, dependent children and other dependent persons, children during pendency of adoption procedures under chapter 210, children under 26 years of age or for 2 years after the end of the calendar year in which such persons last qualified as dependents under 26 U.S.C. 106, whichever occurs first, and children who are mentally or physically incapable of earning their own living, if due proof of the incapacity is received by the insurer within 31 days of the date upon which the coverage would otherwise be terminated; and