Thanksgiving Planning Requires a Pencil Not a Pen

We're hosting Thanksgiving, as we have done the past few years. So far I know that my Mom and my Sister-in-Law Linda will be here. The rest of our guest list is a bit more fluid.
My brother Dave's youngest son is still playing high school football. He team has gone far in the playoffs. If they win one more game they will play in the state tournament Thanksgiving weekend. Winning means they will probably be eating with us. If they lose, then Dave and family are going away for a quick family vacation, as they have done for the past few years.
My brother Steve's middle child plays high school hockey. His team is in a Thanksgiving tournament. He won't know until Wednesday if he is joining us for Thanksgiving. The schedule is decided as each game is played. Winners play in one bracket. Losing teams play in another bracket.
How do we plan? We plan for everyone to show up. If they do we'll have a full house with lots of noise. If they don't then we'll have leftovers. Either way we're ready for a fun day. Now we just have to wait and see who comes to have fun with us.