Section 8521 Of Article 7. Changes In Administration From California Probate Code >> Division 7. >> Part 2. >> Chapter 4. >> Article 7.

. (a) Unless the will provides otherwise or the court in its discretion orders otherwise, if a vacancy occurs in the office of fewer than all personal representatives, the remaining personal representatives shall complete the administration of the estate.
  (b) The court, on the filing of a petition alleging that a vacancy has occurred in the office of fewer than all personal representatives, may order the clerk to issue appropriate amended letters to the remaining personal representatives.