Except in the case where the deceased former member of a district retirement system leaves a will, no payment shall be made to persons included in any group specified in subdivision (a) of Section 24803, if at the date of death of any person or persons to whom any benefit is payable by a district retirement system there are living persons in any of the groups preceding it, as listed. Payment to the persons in any group, upon receipt from them of an affidavit upon a form supplied by the system, that there were no surviving individuals in the groups preceding it, or that they are one of the beneficiaries in any group specified in subdivision (a) of Section 24803 under the will of the deceased former member, and that the estate of the deceased will not be administered, is in full discharge of the liability of the board and system on account of the death.