To be annoyed DH’s niece is now coming on holiday with us

I meant to the treats, outings and all. They are paying flights and all the rest.

she is paying for the house and it looks like she is going to have more space than she thought.

there is nothing wrong in inviting her niece but if she already asked someone else, it should have been discussed. If prearrangements are moved, then no adults should be told any decision to the risk of making feel ackward and not coming. Which is now happening. I can’t blame them either 🤷🏼‍♀️

I think this is reasonable:

DS is a boy. DN is a girl. Surely your family will acknowledge the awkwardness of having a teenage boy in with female family members?

DN should definitely share - there's a privacy element otherwise. DS isn't a small child at 14 anymore, he's a teen

Why can't niece share with grandma? Niece pays for own food and spending (or grandma??) Absolute minimum requirement if she invited someone else.

This has to be done. If you don't have a good time with this arrangement then you do not go again.

Totally agree about niece’s meals etc, at 24 she is an adult, who should be contributing her share.

@MrsWhites Cripes, thanks for the reminder that the niece is 24, I’d overlooked that. In that case, the OP’s immediate family definitely shouldn’t contribute towards her holiday outings, etc., she’s a full-blown adult, ffs. 24-year-olds are financially independent, aren’t they? I certainly was.

You can't put a teenage boy with grandma. I'd cancel and say it was due to insufficient room.

Fair point.

I hope your son doesn't have to share. It's not fair.

It's so inappropriate for you mil to expect your son to share with her and just because he's trying to be nice you know deep down that he won't be comfortable. Tell her to ask her niece of she would have shared a room with her grandad at 14? I'd be inclined to put him in the living room, suck it up this year and refuse to book next year to go

You can’t demand that the bedroom arrangements won’t be changing when you haven’t paid for the accommodation. Unfortunately since MIL has paid for the accommodation it’s ultimately up to her who sleeps where - of course you don’t have to go but I don’t see that you can dictate who sleeps in each room.

Totally agree about niece’s meals etc, at 24 she is an adult, who should be contributing her share.

I agree with your DH. If DS and MIL are both comfortable sharing I don't see the issue. If one was uncomfortable different story but they're not. I also don't think DS sleeping on the couch would be an issue. You are getting the accommodation for free so you shouldn't be expecting everything your way. If you're not happy sort your own accommodation.
Sounds like MIL sees her GD is having a difficult time and wants to treat her. It would be very unreasonable for you to get in the way of that.

On reflection I wouldn't have wanted to share a bedroom with my grandfather when I was 14/15. I'd have found it extremely embarrassing despite being very close.

I have a 14 yr old and would not expect him
to share with Gran. I think a tent in the garden might be the best bet.

Could DH speak to his brother regarding making sure niece has spending money for meals out etc so you’re not subsidising her so much? I know she’s an adult, but might reduce arguments on holiday.

Spontaneous erections. HTH.

@ToxicChristmas has a great suggestion, could you get a refund on your ticket? Your family should definitely not subsidize your niece on this holiday, your MIL invited her so she can pay and arrange for the niece’s parents to reimburse her if necessary.

Presumably you don't let your husband share a hotel family room with your kids then.

Why on earth would grandma be aware if it happened to DGS? They're not sharing a bed.

I don’t think your DS should share a room with grandma, that should be the niece. That sad I don’t agree all these comments that it can’t happen. My son lives with his grandma, he’s 30 and shares a room on her on holidays. None are bothered and can afford their own rooms but choose to share. I see zero issue with it, they’ve always been close. DS2 who is 19 and not as close to his Nanna id say maybe they shouldn’t but it’s nothing inappropriate. But should be the niece sharing given she’s the extra body and she’s the same gender

Teenage boys are entitled to privacy in their bedrooms. If you don't agree with that feel free.

Nobody heard of Morning Wood?

What have the "throws of puberty" have to do with sleeping? I mean would the world come to an end if they both nodded off in the garden/car/lounge?

A 14 year old boy in the throws of puberty is entitled to privacy in his bedroom. I understand why the idea of sharing a bedroom with his grandmother makes the OP feel uncomfortable.

No one is explaining what is so outrageous about the 14 year old sharing with grandma when they are both happy with the situation.

I don't think it's unreasonable that MIL has booked niece to come but I can understand why you would have liked to be informed prior to booking.
And niece definitely has to share bedroom with MIL. Niece may be friendly and helpful now ( teenagerhood is difficult). I think you need to make an effort; if the situation is strained, your niece and MIL can have separate days out.

This. It's blatantly wrong to expect a 14 year old boy to share a room with his grandmother unless in an emergency.

Grandma IS paying. She's paying for the whole bloody house!

Her grandaughter's relationship has ended. Presumably she's pretty upset. So Grandma did a nice thing and invited her too, and paid her airfare. I still can't for the life of me see what's wrong with that. She has her other grandchildren staying, what's one more? And one who she perceives needs a treat.

As for whether niece is golden child, who knows? It's impossible to compare the relationship that a GM has with a 25 year old DGD, with that with a 14 year old DGS or a 3 year old DGD. And niece and a 3 year old? I wouldn't have engaged that much at 25 either.

I agree with this. Why can't DN share with her granny?