Tell DDIL's father that you will not be cooking christmas dinner this year, so sad as you are about it, you think it would be about it, you think it would be better not to accept the lovely turkey this year?
Or accept it anyway, do what you usually do with it, and carve all the crown meat. Buy a million or so rolls and make turkey sandwiches. Frozen in sandwiches, the texture will not be obvious, and you can eat them at your leisure, adding chutney, salad, cranberry sauce, whatever, to vary them. I used to freeze the last of the Sunday roast like that regularly, and have a supply of ready-made picnics and lunches.
You may then find that you need to buy a bigger freezer - see another thread "Economy v Expense"