When the girlfriend moved in a few years ago, Oliver used to eat her cat's food and snack on the "tootsie rolls" in the litter box. <_<
To stop this, I installed a cat flap on the bathroom door, along with a door closer. This has worked wonderfully. After Oliver went to the bridge and we brought home Olivia, things went well, until she discovered she could fit thru the cat door.
For a time, Olivia would get into the bathroom and, along with doing what Oliver did, she would annoy the cat who used the bathroom as a retreat.
I knew however, time would work against Olivia and we could finally relax. That time has now arrived.....