Since being married my husband and I have always alternated Christmas Day with his parents and siblings or mine. Rather than always spending Boxing Day with the other side of the family, if we are with his family, we usually stay for a couple of days and then see my family later in the holiday. Since having DD1, if we've been with my family on Christmas Day then we are with his family on Boxing Day and stay for a couple of days after.
COVID times meant we got out of sync with one of his brothers. My MIL and BIL + family have gone ahead and decided they will be together 24th - 25th this year and are requesting that we spend 25th with them because BIL will be seeing his in-laws on 26th. We only found out this decision had been made because we were hoping we could line up our plans with BILs in advance of speaking to MIL. MIL and BIL say that we decided we would all be together on 25th in January but I honestly don't remember this at all (and neither does DH).
It's my family's "turn" this year and I don't really want to change plans as we didn't even have a meal with them last year due to us having a newborn. Because MIL is so keen to have everyone together, last year we had a weekend with them and BIL's family in January when our little one was a month old. Before anyone suggests it, spending time with either side on 24th is out because that's our youngest's birthday and it's time for just our family unit to be together.
My mum is always very understanding and says I should do what I think is best but my sister and brother will definitely be disappointed since they're cooking this year.
We are fortunate enough to see both sides of the family regularly so can't use that as a decider. MIL is the kind of person who always seems to manage to get what she wants. No one really stands up to her and on the few occasions it has happened she's got upset. I do get on well with MIL usually but I feel that this is particularly unfair on us, especially since we have the little one's birthday on Christmas Eve. She's also saying that if we don't change it this year then we will always be out of sync which feels a bit guilt trippy to me. Any suggestions on solutions and how to keep everyone happy?