It might be simpler to leave the LCD shield alone and use another pin on the other shield. LCD shields typically provide points for wiring on pins D0-D7 with this sort of thing in mind, but I have never seen a point on pin 9. This means that you would have to wire to the top of the pin. I had a clash between LCD and the main board but I kept the LCD pin and ran a jumper on the intervening proto shield.