I had to laugh that Snoopy misbehaved at the vets. I always feel like I am a bad mother and not training my "children" very well when they act up at the vets.

But if someone grabbed your foot and tried to cut your toenails you would act up too!

My three always want to eat together.........but they don't eat the same thing. Annie and Rascal share a plate of wet food - and Emma hangs around until they are eating and then she goes over to her dry food and eats.
Emma doesn't eat wet food at all.

As someone has suggested, maybe feeding them all the same thing would work for you.

At least you now know who it is.