Should we sleep separately so children can have separate rooms?

This.

Can you read? You seem to have completely missed a vital component in all of this.

I thought their mum was being precious until you said the older girl was regularly being hit. No child should have to put up with physical abuse and so they need their own rooms or they shouldn't be staying over at your shared home.

Could he have them at his parents until you can fix it, if they have the space?

Urgh, the audacity of some people. Their mother, that is. No, don't move bedrooms or give up your bedroom. Perfectly reasonable to expect two girls of similar age to share. If they can't get on, look at a way of dividing their room up.

Mum doesn't get a say what happens in your house unless either of her girls is actually unsafe at your house. Having said that making an autistic kid prone to meltdowns and another kid share seems unfair to both of them.

I think if this is a long term home then I’d look at a room divider. A decent double will make two cosy singles. There’s lots of Pinterest ideas. I divided a room which was easy in a way as had two windows. Cost about £1200 to put up stud wall, plaster and alter electrics for lights. Put in a wall mounted electric heater for the one with no radiator.

I shared with my sister growing up till we were adults with no issues. My boys (2 years apart) can not share if they aren’t fighting they are messing around. Hence room division, some kids just don’t share well

Of course it is. If you are the eldest child you get used to the fact that siblings come alone and you have to share everything.

Son and eldest daughter share, autistic child gets the box room with the view to have a loft conversion as soon as you can afford.

I think both you and your partner (of whom we hear so little...) are unreasonable - for letting the DSDs' mother meddle, and for not proactively working on a better solution for your older child who is getting hit by her younger sister. Kids aren't owed their own bedroom, but they deserve a safe space in every home.

Good for you but not relevant to the thread.

Room divider for 2DDs. It’s two days a week.

You don’t want to accommodate violence, you want to mitigate it (duh) with as little drama as possible.

Think their mum is massively overstepping just because she can. Who knows what she would do if the shoe was on the other foot! Outrageous for you to not have a child of your own so two sisters don't have to share a room. Obvs if you could easily afford to move that would be different. If you can find a solution that would be ideal but no way should a 2yr old be uprooted either, people seem to be forgetting how how delicate toddler sleep is and the massive impact that can have on the parents wellbeing. Nor should older sister have her sleep disturbed by toddlers sleep routine. No doubt they would wake the other with different sleep schedules. A divider or one sibling in the living room would be the ideal solution. Ex shouldn't be dictating what goes on between you & your husband either. Good luck OP.

I’ve never heard such entitled twaddle! God forbid that siblings share a room, just think of the psychological damage that causes. My brothers shared a room, and god did they fight, proper fighting. My parents, other than separating them during the fights left them to it, they couldn’t afford to buy a 4 bedroom house, so brothers had to put up with each other. They are incredibly close and often joke about who had the smelliest feet or worse farts.

They are siblings of the same sex it’s reasonable for them to share. Perhaps it would be better them coming at different times or maybe the one who isn’t autistic can share with her brother.

I shared with all of my siblings until I was 10.

Why did the father think it was ok to put the girls in the same
room? It’s very common for autistic people to need extra privacy. Without space for decompression and to truly relax, the anxiety just doesn’t stop.

how involved is he with parenting? Does he understand his daughter and can he be trusted with her care?

Son stays in his room. Girls share, but if the autistic girl misbehaves she sleeps on a sofa bed in your room . That way you can keep an eye on her behaviour in the hope it improves.

Because everyone has the money to do this.

It's not fair on the older daughter to have to share if her sister is violent. She should at least have an option to sleep somewhere safe when her sister is struggling. She could share the big room with your son when they visit and the younger sister have the box room alone. It is a bit unfair on the 9 year old and your son but everyone will be safe that way. The younger one might be better able to regulate her behaviour with tge right support in a year or two or you might need to think a better option. You don't want the oldest to not want to visit.

I think at the very least the dad should be expected to keep his DC safe whilst in his care.

I think that’s the bare minimum that should be required.

If I felt my DC were unsafe at their dads house, then I’d be stopping them from going and I assume the majority of MN would agree.

Whilst sharing they are unsafe and so I don’t think it’s unreasonable for the mum to expect them be put in separate rooms, just like OP wouldn’t be unreasonable to not want the volatile child sharing with her son.

How they do this is up to them and not the mum though.
But she does have a right to ask him to keep them safe from harm.

Is the girls bedroom big enough to be divided to allocate each of them individual space?

You'd think he would know that his daughter needs her own space?

It smacks of a bit of a useless dad who doesn’t know or indersrand his own kids - and that's why his ex wife is pissed off.

What? Some of these posts are bat shit! Op and her dh either having no bedroom and a sofa bed in the living room or their son having to share his parents room?
nothing said about behaviour management?

If they don't share a bedroom at mum's house this may have never been an issue they've had to face before? Nobody would have known how they would react to sharing a room before they did so, especially if she isn't usually "unkind" to her sister during the day when they interact.

I admit a room each would work better but we had no idea she would be unkind to her sister and I’d rather work on that behaviour than accommodate it.

You have to parent and step-parent the children that you have, not the ones that you thought you would have.