Cal. Prob. Code § 1003

(a) The court may, on its own motion or on request of a personal representative, guardian, conservator, trustee, or other interested person, appoint a guardian ad litem at any stage of a proceeding under this code to represent the interest of any of the following persons, if the court determines that representation of the interest otherwise would be inadequate:
1. (1) A minor.
2. (2) A person who lacks legal capacity to make decisions.
3. (3) An unborn beneficiary.
4. (4) An unascertained person.
5. (5) A person whose identity or address is unknown.
6. (6) A designated class of persons who are not ascertained or are not in being.
(b) If not precluded by a conflict of interest, a guardian ad litem may be appointed to represent several persons or interests.
(c) The reasonable expenses of the guardian ad litem, including compensation and attorney’s fees, shall be determined by the court and paid as the court orders, either out of the property of the estate involved or by the petitioner or from any other source as the court orders.
(d) Before a court appoints a guardian ad litem pursuant to this chapter, a proposed guardian ad litem shall disclose both of the following to the court and all parties to the action or proceeding:
1. (1) Any known actual or potential conflicts of interest that would or might arise from the appointment.
2. (2) Any familial or affiliate relationship the proposed guardian ad litem has with any of the parties.
(e) If a guardian ad litem becomes aware that a potential conflict of interest has become an actual conflict of interest or that a new potential or actual conflict of interest exists, the guardian ad litem shall promptly disclose the conflict of interest to the court.