Except as otherwise ordered in formal proceedings, if a personal representative is appointed and then, at a later time, the will under which he is acting is invalidated or if a will is later proved, changing an assumption of intestacy under which the personal representative is acting, his office is not automatically terminated although his powers may be reduced as provided in Section 3-401 [45-3-401 N.M. Stat. Ann.]. The personal representative’s office terminates only on appointment of a new personal representative. If no new personal representative is sought, the existing personal representative can continue to act under the new testacy status.