Hi cloclo
Do you have a utility room or some room thats not often used where you could maybe put the tray and bowls up on the work surface out of reach of Grace?
If you have a cat flap maybe you could train your cat always to do her business outside then you'll only have the food bowls to worry about.
We have 3 cats and their tray is in our conservatory where Ben won't be allowed once he's crawling - only cos its a ramshackle conservatory that leaks, is freezing and could fall down at any moment!!
Poor cats!!
xx