(a) The director shall approve any amendment to a voluntary plan adjusting the provisions thereof as to periods after the effective date of the amendment as to which he or she finds that the plan, as amended, will conform to the standards set forth in Section 3254, and that any of the following exist:

1. (1) A majority of the employees covered by the plan have consented in writing to the amendment.
2. (2) All of the employees covered by the plan who are adversely affected by the amendment have consented in writing to the amendment.
3. (3) The insurer of such plan, if any, has certified to the director that notice of the amendment either separately or as a part of a new certificate or statement of coverage, has, at least 10 days prior to the effective date of the proposed amendment, been delivered to the employer for distribution to his or her employees within 10 days thereafter and has further certified that such notice specifically included notification to the employees covered by the plan of their right to withdraw from the plan.