I should have made a note of what I did last year, but didn't!!
First evening party, Multiwave bolus as late getting there and very hungry. Stayed on target by eating sensibly, and walking home.
Last night, checked and had gone up to 20 as I was talking to people and forgot to do an extra bolus, corrected and hypoed three hours later (note to check correction dose but when eating normally)
Two parties today, grazing through afternoon and early evening and used extended bolus and then ate to match what I had put in. Much more sensible and on target. Just injected for a piece of Christmas Cake and cheese, so waiting for about 20 minutes before tucking in.
Tomorrow?? A bit of this and that and correction after walking home late in the evening.
Most of all my advice, is do the best you can (if you are very organised make a note of what works and stick it in your Christmas Recipe book) and enjoy yourself.