To expect uninvited guests to fit in around us?

[RockingMyFiftiesNot]

I need to be deliberately vague here....
Relatives have invited themselves to spend Christmas with us. I understand why, have said yes and they will be made very welcome.
I'm massively committed in December so am trying to get on top of planning for Christmas now. Had a zoom with them tonight as one of them has some dietary requirements I needed to be clear about
They then asked about what we would be doing on the days they are with us - and proceeded to say they didn't like x, y, and z, wanted Christmas Day to be done a certain way etc etc. I was proud of myself that I didn't tell them to F off; but they are under the impression that as they are guests, they get to call the shots. Don't want to drip feed so need to add that reason they wanted to be with us is so that they can be near an elderly relative who won't make another Christmas, which complicates things somewhat.

Not quite sure how to handle: we've already had our Christmas turned upside down to an extent by saying yes to their self-invitation, so I don't want to have to further change our plans because they want Christmas in our home to be a replication of Christmas in their home.

Not sure if that makes sense, whether I'm being inhospitable, or just over complicating things?

I’ve never produced a Xmas dinner that’s ever been on time anyway. Time becomes flexible. Dishing one up at noon or 1pm wouldn’t be happening.

I certainly wouldn’t be busting a gut to do it over someone else’s waistline worries

I really agree with @WhereYouLeftIt This is a polite, fair, considerate and truthful way of making sure your own Christmas isn't ruined by atmospheres and resentment.

It'll help you be more assertive in the future too, maybe even to the point where you respond in person/by Zoom at the time, instead of having to shelter behind a later-sent letter. (Not having a go at you - I'm not assertive on my own behalf either, though funnily enough I can be a lioness on behalf of someone else!)

We are so please to have you be a part of our Christmas and enjoy our traditions.

How did it go op?!

Thanks for asking @Pirrin. Christmas Day went really well, They accepted that I couldn't move meal to suit them as our DC already had plans with their in laws before coming to us for dinner, but I worked other things around them so they were happy. We all saw our relative Christmas Eve and Boxing Day (he was with his immediate family on Christmas Day). Guests will go home first thing tomorrow so are currently packing and are getting us a takeaway tonight. All good thanks x

Glad it went well OP.

Phew, so pleased for you that it was OK!

Thank you, and thanks to everyone who helped me work this through last month - it was massively stressing me out and I couldn't see straight. A little bit of gentle assertiveness did the trick!