To put my foot down and go to DMs for Christmas

[Tiggles]

(Namechanged as SIL may be on MN!)
Some back story:
I have 3 DSs aged 10, 6 and 5.
I have a brother with twin boys aged 8 and a DD6.
My DM has told me she prefers my brothers children to mine (she always wanted twins) but recently has admitted that actually mine are not as badly behaved as she has made out, and they are perfectly nice children. Don't get me wrong - my kids aren't angels, they have high functioning autism syndrome but they try their best.
However, because of this preference she often cancels on me e.g. we were going to stay with her one summer and then she said not to come as she had invited DB and his kids instead. Or she suddenly decides not to come to stay and goes to stay with DB instead (we both live 7hours drive away from DM, but apparently it takes longer to get to us).
Every year since brothers twins born they have gone to DMs one year, and she has gone to them the next. I have offered to come to us, but it has never materialised.
The AIBU
This summer, when I was staying, she said that my brother wasn't coming this year. So I said maybe me and the boys could come and stay as they had never seen her on Christmas day before. She agreed. A couple of weeks ago, having rechecked it was ok, I told the boys they would be going to granny's for Christmas - having autism they need preparing in advance.
DB and DSIL are now not very happy as DM apparently said she would go to them on Christmas Day, and now they are struggling when DM can come and stay with them as they also want the other grandparents to come and stay for new year.
AIBU to put my foot down and say that, actually, this time, I'm not changing my plans for them and we will be at DM's for Christmas?

I don't know about your dc op, but many autistic kids would do better in their own home on Christmas. They can stick to their routine, have all favourite things around them (wear pjs all day?). Why not make Christmas a special day just for your family.

I would tell DM that if she backs out if this one, she has let your children down one time too many and you will make no further efforts to retain contact on your part. However I might compromise by inviting her to come to you for Xmas. Then she could easily drive to DB on Boxing day.

I struggle to understand that if you live so close to your DB why you all don't get together for a full family xmas? or you all go to your mums. do you see your brother?

Granny is not stuck between a rock and hard place. She invited OP and her family for christmas. Now BIL & SIL have decided they don't like it, well tough OP mum has already made arrangement this year for christmas so she can visit them another time.

I would also make a mental note that A) she explains to your dc why she changed her mind and B) that you will never be going there again if she want's to see you and you dc she can come to you,

Good luck, whatever you choose to do.

I do feel sorry for you but you say that your children are aware that the other grandchildren often see granny for Christmas. How do they know this, did you tell them? If you did tell them then I would advise not telling them things they don't need to know.

very un comfortable.

I am not sure I would want to go to hers for xmas after all you have said.

I would be very wary exposing your dc to her, my GM treated her GC very differently, or maybe it was not that differently, but my DB has never forgotten it and has given him a chip tbh.

I know we could do Christmas on our own again, but we have done that for 10 of the last 11 years (when DS1 was small we all met up one year at DBs house) and it would be nice to do something different. (DH's family all live abroad, so we don't often see them).
They know that the cousins spend Christmas at Granny's as she has lots of photos out when we go and stay.

YABU. You're not doing anyone any favours by insisting on going somewhere you and your family will be second choice.

Can I just say,

They may not realise she doesn't like them very much now

But they will.

I would ensure now that they lose interest in her totally so when the time comes they do not give a fuck about her at all.

She sounds awful

you shoudl cut her out