Group disability insurance is hereby declared to be that form of disability insurance covering groups of persons as defined in this section, with or without one or more members of their families or one or more of their dependents, or covering one or more members of the families or one or more dependents of such groups of persons, and issued upon the following basis:

(1) Under a policy issued to an employer or trustees of a fund established by an employer, who shall be deemed the policyholder, insuring employees of such employer for the benefit of persons other than the employer. The term "employees" as used in this subdivision shall be deemed to include the officers, managers, and employees of the employer, the individual proprietor or partner if the employer is an individual proprietor or partnership, the officers, managers, and employees of subsidiary or affiliated corporations and the individual proprietors, partners, and employees of individuals and firms if the business of the employer and such individual or firm is under common control through stock ownership, contract, or otherwise. The term "employees" as used in this subdivision may include retired employees. A policy issued to insure employees of a public body may provide that the term "employees" shall include elected or appointed officials. The policy may provide that the term "employees" shall include the trustees or their employees, or both, if their duties are principally connected with such trusteeship;

(2) Under a policy issued to an association, including a labor union, which shall have a constitution and bylaws and which has been organized and is maintained in good faith for purposes other than that of obtaining insurance, insuring members, employees, or employees of members of the association for the benefit of persons other than the association or its officers or trustees. The term "employees" as used in this subdivision may include retired employees;

(3) Under a policy issued to the trustees of a fund established by two or more employers in the same or related industry, or by one or more labor unions, or by one or more employers and one or more labor unions or by an association as defined in subdivision (2) of this section, which trustees shall be deemed the policyholder, to insure employees of the employers, or members of the unions or of such association or employees of members of such association for the benefit of persons other than the employers, or the unions or such association. The term "employees" as used in this subdivision may include the officers, managers, and employees of the employer and the individual proprietor or partners if the employer is an individual proprietor or partnership. The term "employees" as used in this subdivision may include retired employees. The policy may provide that the term "employees" shall include the trustees or their employees, or both, if their duties are principally connected with such trusteeship;

(4) Under a policy issued to any person or organization to which a policy of group life insurance may be issued or delivered in this state to insure any class, or classes, of individuals that could be insured under such group life policy;

(5) Under a policy issued to cover any other substantially similar group which, in the discretion of the commissioner, may be subject to the issuance of a group disability policy or contract; or

(6) Any group disability policy which contains provisions for the payment by the insurer of benefits for expenses incurred on account of hospital, nursing, medical or surgical services for members of the family or dependents of a person in the insured group may provide for the continuation of such benefit provisions or any part, or parts, thereof after the death of the person in the insured group.