This actually happened to me!!!!!!
My husbands family is exactly the same. We all get together a week or 10 days before Christmas (it has to be convenient for the out of towners) and everyone brings something. One SIL brings curried cauliflower, BIL brings veggie tray with dip, inlaws supply ham and/or turkey, mashed potatoes, gravy. I am always asked to bring the same boring thing....my mustard glazed carrots. They rave every year over this and it is simply brown sugar, butter and regular mustard over boiled carrots. DH keeps saying "you can make so much better stuff, so why don't you?". So last year I made a brussel sprouts casserole with bacon and cheese, and rice stuffing balls.
As they were unpacking the food to put in the oven to warm, everyone was literally looking for the carrots, not paying any attention to the other dishes. So, I sent DH to the car to get the container of carrots I had already cut up and ready to go and the little dish of the glaze I packed, for just such an "emergency".
They all said the other dishes were okay, but I sure scared them when they thought I didn't bring the carrots.
Hopefully your family is a little more flexible.