The township clerk may appoint a deputy for whose acts the township clerk is responsible. Before a deputy clerk enters upon the duties of the office, the deputy clerk shall take and subscribe the oath required by the Constitution of North Dakota and shall file the same in the office of the clerk of the district court. In those townships in which the offices of township clerk and treasurer have been merged, the person elected to fill the new office shall appoint a deputy only after receiving the approval of the board of township supervisors.