I've just found out that DH has been assuming (and his family are therefore expecting) that we're going down to spend Boxing Day with them.
To explain the background, like many couples, we've agreed that Christmases will be spent with alternate families. Last year we went to his family for Christmas and this year we'll be spending it at home with my mum. For me, spending Christmas at home doesn't involve chucking my mother out on Boxing Day morning and racing down to Kent to see DH's (large) family for the day. I consider Boxing Day still part of "Christmas" and want to spend a relaxing day at home with DH, DS (age 2) and my mum - I know that Christmas day will be fun, but it will also be tiring - I inevitably end up doing most of the cooking and this year I'm pregnant to boot.
Last year, my mum came to visit us after Christmas, but not until 27th December, giving us Boxing Day to return from DH's family and have a relaxing day at home together. I would have absolutely no problem with going down to see DH's family on 27th this year but don't see why it has to be on Boxing Day itself (particularly as this year, 27th is a Bank Holiday so everyone will be off work anyway).
I realise that Christmas is often a compromise when you have different families and traditions to include, but I thought that's what the alternate idea was all about - not that we'd end up effectively spending every Christmas in two places and only alternating Christmas Day itself... AIBU?