When I first took in Wink as a foster kitty, he had horrible diabetic neuropathy. Couldn't jump, had a hard time with stairs, climbing skills were non-existent. Once he got better, I had to put all food out of his reach because he could jump everywhere! I've found him up on the dining room table, his head down in my breakfast cereal. I only turned my back for a minute to grab my orange juice! ohmygod_smile
I imagine it's even more difficult with Marley and young kids that don't understand about their kitty not being able to have any people food. Marley is your 'clean up crew', so it's going to be a challenge for you to keep him out of that contraband food.
Now, if I drop a piece of cereal on the floor, I immediately reach down to pick it up. I don't leave any food in Winks reach, which means bread in a cupboard, nothing left out on the counter, nothing left in the sink after scraping the plates for the dishwasher, all food in cabinets or in the fridge. For me it means I have to be careful carrying in the groceries from the car, shut the kitties behind closed doors and put the groceries on the counter and put them away immediately. I used to put some of the bags down on the floor, but not anymore after Wink stuck his head in a bag and started munching on some food.