SIL and Christmas

[Toomuch2019]

So DH is one of 3, DH, BIL and SIL.

BIL hosts my in-laws 1 out of 3 Christmases. SIL hasn't hosted them for the last 20 years that she has had kids, preferring to spend Christmas as a nuclear family unit and not inviting anyone other than the 5 of them. Which is fair enough but has meant we have hosted the in-laws 2 out of 3 Christmases along with my parents. My in-laws are very welcome and we love to have them, them and my parents get along well and we all have a great time.

This year SIL is going through a divorce, and invited herself to the in-laws. We have extended the invite to her and any of her now adult children that wish to join for dinner and I have
already ordered a large turkey to accommodate.

However SIL has now asked for the in-laws to cook for her and her "kids" (adults). She thinks one of her sons (who she hasn't actually spoken to for the last 3 months so is 2nd hand through another son) will only come if they don't have to come to ours for lunch as they don't want to hang out with my family! Not only offended but think son attending is pretty unlikely anyway given they aren't speaking to SIL.

In laws are going along with this ridiculousness because SIL has had a hard year. But they are now now trying to get us to give up our Boxing Day pyjama day to do a second Christmas with them. I don't want to go there. I'll be tired after running around at Christmas hosting my parents and want to hang out with my young DC and their toys.

I obviously will be gracious and won't argue about this as I love my in-laws but AIBU to be annoyed about this situation?
Also WIBU to say that's fine they are hosting SIL for Christmas but refuse to give up my Boxing Day just because they don't feel they can say no to SIL?

@billy1966

20 years your SIL has suited herself.

You sound very kind but a bit of a pushover.

Your in laws are choosing to do something else and change THEIR plans but you do not have to change YOUR plans on Boxing Day.

I certainly wouldn't in your place.
This is a tradition in your family that the children enjoy so I would be saying just that.

Doing a MUCH simpler toned down lunch another day would be very generous.

Your SIL sounds like she is used to getting her way and this could be the start of a pattern so you would be wise to be kind but FIRM with your boundaries.

Everything they said x100.

"Your SIL sounds like she is used to getting her way".

Is it possible she's had to give in to her husband's demands that it be 'just the 5 of them' for the past 20 years but now at last she's free of him and can spend it with her family?

OP I vote for your family doing its usual thing on Boxing Day but you making festive plans with the PIL on an alternative day if you can.

Update - DH has phoned DMIL and said firstly they are very welcome still if they change their minds for any reason. Esp as DH is convinced nephew won't come anyway. But if not we will see them a day that isn't Boxing Day. MIL seems ok with that

Thanks all for your input

Well done OP.