(a) The primary insured or guaranteed amount for share and deposit accounts of individual members of participating credit unions shall never be less than the corresponding share insurance coverage provided by the NCUSIF or its successor.(b) With the approval of the commissioner and if authorized by the insuring organization, a participating credit union may, from time to time as determined by its board of directors, issue membership shares that are not guaranteed and are subordinate to all other claims, including creditors, shareholders and the insuring organization.