I solve the problem by preparing MORE than I think we'll eat. By the time the snitchers have their way with my food, I usually end up with the correct amount.
Good Luck with the varmit hunt. I totally understand your frustration with the invader and I wish you luck at nabbing the intruder.
Don't forget, I took out the rabbit who was chewing on the Endless Summer Hydranga given to us in my late FIL's memory. If you need help with the hunt, give me a call, I'll be right there with my trusty 22.
I do the same thing, expecially the deviled eggs and the relish dish. When the turkey comes out of the oven, the snitchers are really busy trying to get a pice of the slightly over-browned skin. YUK, but they love it. I seldom serve sliced turkey with skin. I lay out plastic spoons and an empty "trash" can, for the mashed potatoes. All I put in the potatoes is salt pepper and cream cheese and a bit of milk.