Cal. Probate Code - PROB § 9620. Section 9620.
If there is a dispute relating to the estate between the personal representative and a third person, the personal representative may do either of the following:
(a)
Enter into an agreement in writing with the third person to refer the dispute to a temporary judge designated in the agreement. The agreement shall be filed with the clerk, who shall thereupon, with the approval of the court, enter an order referring the matter to the designated person. The temporary judge shall proceed promptly to hear and determine the matter in controversy by summary procedure, without pleadings or discovery. The decision of the designated person is subject to Section 632 of the Code of Civil Procedure. Judgment shall be entered on the decision and shall be as valid and effective as if rendered by a judge of the court in an action against the personal representative or the third person commenced by ordinary process.
(b)
Enter into an agreement in writing with the third person that a judge, pursuant to the agreement and with the written consent of the judge, both filed with the clerk within the time specified in Section 9353 for bringing an independent suit on the matter in dispute, may hear and determine the dispute pursuant to the procedure provided in subdivision (a).