I have a long crack in my ceiling which has come back after being filled probably due to other work going on in the house. It stems from one side to the other. My plasterer is suggesting 'tacking' boards to the existing. Im aiming to take the old plaster and lathe ceiling down and fixing plasterboard to the joists. Is there any possibility of digging out the crack, filling it, taping over it. Is my plasterer right or wrong in sayng that new ceiling should go up?