As the UBM, I was a convenient excuse for having Thanksgiving a big dinner. I bought the bird, and I prepared it and the pumpkin pies (though she did the dressing, potatoes, side dishes etc.). Just don't utter the "T" word, and don't invite the relatives.
As usual, they are willing to "partake" of the superficial holiday trappings, so long as they deny any and all spiritual meaning for the occasion. They can be the most sort of worldly people during the holidays!