In a declaration of trust entered into by an officer of the Postmaster - General's Department before the commencing day with respect to moneys payable under the Commonwealth Public Service Act 1922 or under that Act as subsequently amended to a dependant of a deceased officer of that Department, a reference to the Director - General of Posts and Telegraphs, a Chief Officer of the Postmaster - General's Department or a person holding any other office in that Department shall, on and after the commencing day, be read as a reference to the Minister.