California Code, Education Code - EDC § 24331

(a) An option beneficiary or a trustee or beneficiary of a trust that is an option beneficiary who is receiving an allowance pursuant to the option elected by the member may designate a beneficiary to receive any allowance that has accrued and is unpaid, and any remaining balance of the retired member's accumulated retirement contributions payable pursuant to Section 23881, upon the death of the option beneficiary.

(b) Unless otherwise specified in the trust instrument, the trustee of the trust that is an option beneficiary is entitled to name a subsequent beneficiary if the trust is valid. If the trust is determined to be invalid or terminates, any election by the trustee pursuant to this division shall be void and the beneficiary shall be entitled to exercise all rights provided to option beneficiaries under this part.