(1) Where a safe deposit box is made available by a lessor to one or more persons acting as fiduciaries, the lessor may, except as otherwise expressly provided in the lease or the instrument of authority pursuant to which such fiduciaries are acting and copies of which have been furnished the lessor, allow access thereto as follows:
(a) By any one or more of the persons acting as executors or administrators;
(b) By any one or more of the persons otherwise acting as fiduciaries when authorized in writing and signed by all other persons so acting;
(c) By any agent authorized in writing and signed by all of the persons acting as fiduciaries.