I understand what you are going through. We have the same problem with Thanksgiving. This year I invited everyone to our house for Thanksgiving. My one sister-in-law stated that Thanksgiving was "her holiday" and declined. The other brother's family never even replied. I asked my Mother when we had chosen "our holidays"? She chuckled. I have officially chosen Groundhog's Day as my holiday.
Enjoy Christmas with your family and don't let your sister and "her holiday" ruin it.