The lives of a group of individuals may be insured under a policy issued to a credit union or to the trustees of a fund established by one or more credit unions, which credit union or trustees shall be deemed to be the policyholder for the purpose of this section, for the benefit of some person or persons other than the credit union or credit unions or trustees or any of their officials, and subject to the following requirements:
(1) The members of a credit union eligible for insurance shall be all of the members of the credit union or all of any class or classes thereof determined by conditions pertaining to their age or to their membership in the credit union or to both;