To want to have one meal over Christmas as a family?

Spend Christmas day with DD. Ask him if you and DD can come a bit earlier on boxing day before the inlaws arrive. Maybe bring some things to do a nice light brunch for them.

His girlfriend only "gets" to spend Christmas alone with her parents because he's volunteered to work.

I don’t get the big deal of needing to get adult siblings together for Christmas. It’s really not that important. Especially considering you haven’t seen yours for years to then make siblings seeing each other this big thing.

OP I know you've had a bit of a flounce because people have been honest with you and called you out for your unreasonableness but:

I'd be concerned your son was being taken advantage of if he struggles to say no due to his disability.

I really don't understand parents of adult children who want to isolate them from their "new" families and have this alone time.

You're invited. Just be cheerful and involved.

You don't need to be suffocating and demanding asking your adult children to spend time alone with you!

I won’t be seeing any of my children over Christmas this year. Since they now live with their partners, we have agreed to spend alternate years with each side of the family, so last year they, and their partners, came with me to our family meal at my sisters house on Christmas Day and then they stayed the night at my house. One lives an hour from me, the other about two hours away.

This year, I am not spending Christmas Day with them but I am hosting a family get together on the 22nd so my siblings can all swap presents with my children and be with my new granddaughter. I will go to my sister for Christmas Day as usual with my other siblings. Had my sister decided not to host, I know I would be welcome at my daughters house along with her partners family - it would be a tight squeeze but that adds to the fun!

I can’t imagine a year when someone in my family did not extend an invite to me, the only one without a partner, my own children would make plans between them to include me.

It’s about being adaptable to changing circumstances with good grace.

It's very ironic that, on reflection, you realise that you haven't seen your own brother for Christmas, whilst fretting over whether your children are seeing each other.

Yep

It's hard but whilst you still consider them your "immediate family", they now have their own immediate family dynamic and this will extend to their partner's parents, so having time alone with lots of different variations will be impossible over the two days. I agree that you should try and arrange something in the lead up if you really need that, but otherwise it sounds like they're both trying to navigate treating both sides of the family equally, which is probably an absolute pain in the arse for them in itself without having to factor in alone time with one side of the family as well

Honestly OP, this is just part of your children growing up. Your children now have their own partners and I think you need to accept Christmas now includes in-laws and partners. Your children are adults then they can arrange to see each other in their own time. I think you need to accept the days of immediate family togethers are over, as hard as it is. Your children aren't small children anymore and Christmas evolves to reflect this. I'd find it really strange now to if my husband or my own family insisted on get togethers without partners present.

It only came up yesterday afternoon that plans had changed.
Who had agreed to this change? We had agreed that if that happened we would move our family meal to Boxing Day. that would be a change to plans of having that day/meal with the dps family? Had that been agreed with them?

Me and my brother have lived 3 hours away from each other for the past 30 years with my parents being 4 hours in another direction and it is nice when we're all together which probably only happens once every couple of years.
In your case, despite you all living much closer together, there are still logistical issues which make it difficult. If it is truly the case that you want to see your DD and DS together and this isn't some sort of one upmanship or favouritism game at play, invite them over one weekend in January when everyone is broke & bored. If space is an issue, perhaps you need to go out for a meal or something. Or even a mid week meal. There are plenty of solutions to this "problem" without making a drama of it. Remember the TV ads are not real life!

It's very ironic that, on reflection, you realise that you haven't seen your own brother for Christmas, whilst fretting over whether your children are seeing each other.

I always say that Christmas is a season, starting December 1st and ending on Twelfth Night. There is plenty of time for a special get together in that time.

But either way, be prepared for life to keep changing as your children grow. We have all sorts of tensions with the ILs as they want us to fall in with their existing Christmas traditions, whilst my parents are happy to fit in with what works for our new family.

It really saps the joy and turns things into an obligation. The best way to keep that joy alive is to not be too intense about idealistic expectations and be open to change.

It’s hard when so many other complexities and constraints enter the ‘who goes where’ equation.

Bringing both sets of parents together is the logical approach for your D.C., really.

I didn’t realise at first that your Ds volunteered to work Christmas Day. Why did he do that, do you think?

I am facing my first Christmas without my Ds and am heartbroken, but of course putting in a brave face and cheering him on, remembering the times in my 20s when I gaily sailed off elsewhere for Christmas. Didn’t mean I didn’t love them.

I don't think anyone has been brutal, just honest about the fact that your expectations need to change now that your kids are adults with their own homes and partners.

Do check with your brother, obliquely, before making plans for yourself. He has for years been quietly enjoying his Christmases without all this fuss.

I just couldnt get tied up in knots over this, maybe because DH worked through the Christmas period year after year when DD was growing up I am use to going with the flow and doing the best we could to make it special. We used to have a delayed Christmas lunch on his one day he had off (27th / 28th etc). The date made no difference, we still spent time as a family.

OP you are seeing your children on Christmas Day & Boxing Day, just be grateful for that. Things change as your children become adults and families of their own.

They are adults. Who cares if they don’t have the same day off. Thats just life.

Do you live near each other? If so, can't your son pop by either before of after work and see you and DD on Christmas Day? You could then have breakfast or dinner/drinks together on the day. He's presumably not working for 16 hours or so.

This story just gets madder. Your OP positioned the six people as the crux of the problem. Clearly the issue is actually that you just want Christmas to be you and your kids (which you know is unreasonable or you’d have said it outright) and that the day you’ve chosen for your alternative to a Christmas Day celebration is one where DD already has plans. Absolutely none of this is your son’s fault and it’s really unfair that both you and DD are acting like it is.

OP - your children have bigger families now. It's no longer just the three of you and you shouldn't expect it to be.

You can't expect your kids to exclude their in-laws on your say-so. That would be incredibly rude. Either embrace the big family Christmas in a squashed home (which is what millions of people do every year) or have your own get together before Christmas or in the New Year if that's what you want.

Or maybe he doesn't struggle with the word 'no' at all and has opted to work instead of spending a special day with you moaning on and living in the past with your expectations that the 'kids' will always be just that to you. I wonder if he'd have taken the Christmas day shift if you treated him as an adult? I have a feeling he could write a book on his mothers expectations and 'disappointments'...

Ah, it's Christmas, it's about families spending time together!

We always have random friends and family joining us as the invite goes out to everyone! And we spend it at my brother's who lives in a 2 bed flat. There's usually around 10 of us at the height!

Just go with it, you'll have fun! You're still seeing your family!

With kindness, as it sounds like this is really difficult for you, you really need to loosen those apron strings.

Your children are adults. You no longer need to manage their relationship. It’s not your job to worry about when they see each other; they’ll work it out if they want to.

Ask DS for the money DD has given him back, buy some ready made Christmas food so that neither of you have to ‘cook’ and enjoy your day with DD.

It sounds like DS has changed the plans and his DP’s family are accommodating you in their plans so be gracious and polite to them (the extra person in the tight dining room is you!)

If you want a family day, arrange something for the end of Jan. people are just about ready to socialise again by then!

Life changes. It's not unreasonable to want that, of course it's not. But this year it's not going to happen, and you just need to accept that. It might not happen again tbh. I can't remember the last time we had a Christmas, just me and my family. One year my daughter stayed away, one year a friend of hers came, one year my son's then girlfriend came, for the last at least four years, other friends of their's have been there.

Both my children have partners now. I think this Christmas there will be at least the five of us, possibly more. Neither of the partners have been with us for Christmas before - but as life for them changes, us parents need to adapt.

Please don't let this get in the way of you enjoying the time that you do get to spend with them, despite not all being together.