K.L.
If you know her drama/trantrum is going to happen and dont have any choice in stopping or avoiding it, then have fun with it!
Talk with the rest of the family, friends and anyone else who will be there, who understands her propensity for drama and causing trouble. Have everyone chip in $5 and make bets on what time she will blow. Just like the baby pools at work when someone is expecting! Maybe have everyone pick a time she will start the drama, and who she aims it at, as a tie breaker. I can just see the fun for everyone to be sitting around happily visiting and sipping eggnog, and when she walks in the "TIME STARTS NOW!" and the eager faces as she starts her little fuss over small stuff. Have someone designated as judge for when it is FULL BLOWN TANTRUM and decides who the winner of the cash is! As she storms out in her dramatic way, the cheers and high 5s for the winner will be so much more fun than any other entertainment you can have!