California Code, Probate Code - PROB § 6347

(a) Except as otherwise provided in the will or ordered by a court, each custodian designated in the will and the person for whom the property is to be held shall be deemed a devisee for the purpose of receiving notices which may be required or permitted to be sent to a devisee in the estate of the testator.

(b) Unless required by the will or ordered by the court, a custodian does not have a duty to participate in the proceedings in the estate on behalf of the minor, and in no event does the custodian have a duty to so participate until the custodian has filed a written notice of acceptance of the office of custodian with the clerk of the court in which administration of the estate of the testator is pending.