To think you don't invite overnight guests to someone else's house?

[Normanpriceisnotarolemodel]

So 5 day before Christmas MIL announces that she wants us to host SIL and DN as well as herself and FIL next weekend. And implied that we are in the wrong for not inviting SIL in the first place. Bearing in mind we are seeing SIL and DN in two weeks time for DN's birthday and have never hosted them at Christmas, I am slightly bemused at this in the first place, never mind the late notice. I'm not unreasonable to think you don't invite overnight guests to someone else's house, am I? Never mind that we don't have enough beds, and I'll now have to arrange bedding, towels, extra food etc etc. Saying 'no' will cause reprisals, she's that kind of woman.

why would he reply in such a passive aggressive way? If you dont want to have them to stay, then dont.

Yet again a MIL issue which is really to do with the husband not dealing with things. If you dont want to do something, then dont. It is that simple

Your DH missed his chance there. His answer should have been of course it's not ok. We will see you as planned in 2 weeks.

If and it is an IF, SIL and DN are going to be on their own I would have already invited them.

That's a rather ridiculous reply for your DH to send, I think.

Your H needs to text again 'sorry, just to be sure, we'll see you as planned on X date, we really don't have the room to have everyone over at the same time, Happy christmas, have a good one'

Of course your MIL is utterly unreasonable.

However, if your SIL and nephew would otherwise be on their own , it'd be a kind gesture to invite them - I might be wide of the mark here, but I'm imagining a single parent whose parents are with her brother, wanting some adult company for the day.

I too would go all PA on MIL , and get her to bring her own extra bedding , towels etc as SIL will now be using all your spares.

No, she's not on her own. Her DH is planning on doing some building work to the house, hence not coming. Plus doesn't get on with MIL, no surprise there.
The latest is DH has said to his sister that his mum was unreasonable to invite extra guests to someone else's house and that if she wanted us to host a family Christmas then it should have been arranged a long time beforehand. However, that they are welcome to come...

And yes, I know that we could and probably should have said no, but all those saying it's easy to say no, it's not you that has to live with the consequences!
I will be making a few choice remarks when they are here, believe me...

What consequences can she possibly inflict on you? Does she employ you? Do you rely on her for childcare? Live in a house that she owns? Fund your lifestyle? What is her power? Does she actually have any or is it just you're so meek that you have to lie back and take whatever sulking or guilt trips she puts on you?

You teach people how to treat you, 'a few choice words' isn't going to achieve anything, it's certainly not going to make anybody respect you.

It's very easy to say no, you just open your mouth and say 'no'. That's it. Nobody can dictate to someone who is direct about what they want, what they're prepared to tolerate and refuses to bow down like a servant and accept what they don't want because someone else tells them to.

Get a spine, demand your husband find his balls and stop indulging your mil. She can't do anything to you unless you're prepared to accept it. So don't.

My SIL (who had prior form for being a right cah) did something similar to me once. She was coming for the w/e with her kids and rang to say, 'Oh, we've got DS1's friend this weekend, it's ok if we bring him, isn't it?'

The idea of hosting an unexpected 12 year old boy that I had never met was more than I was prepared for, so (after years of being a bit of a push-over and biting my tongue) I said, 'Er, actually, no, it isn't. You're all still welcome, of course, but I don't know this boy so I'd rather you didn't bring him.' (Her DC, I should say, were all PITAs and I expected the friend to be just the same - going through my cupboards, making a song and dance about not wanting whatever had been served for lunch, could he have a bis-cuit, oh go on, just one.... Or one of those chocolate bars in the cupboard that I just saw....

SIL was deeply unimpressed. The bonus was that NONE of them came and I don't think she's visited since. Result!

Go for it, OP: say NO.
And install CCTV just in case...

say no.