To want SD’s room to be multifunctional?

You cannot work on the kitchen table, in a smaller house with only a sitting room and kitchen,

get your DH and SD to triak it next weekend she is with you. Seal off dining room as that not exist in new house. Then in a working day ban everyone from kitchen too ( yes know you not work a Sat but pretend). How did they find it being limited to their own bedroom and a lounge for 8 hours?

if DH not convinced, try it Monday-Friday…

seriously 2 choices:
not give ex £700
or do what you need for you in your house.

personally I think you are amazing financing an ex and her 3 children.

You sound fabulous to be honest. Still supporting the sd's mum and carrying the financial burden. Definitely you can't use your ds bedroom as that's just not practical as he lives there. Dining or other busy living area is a no no, I work from home too and that was a nightmare. Just do it. Time it right and she won't even know. It's no different to you going into the room at other times when she's not there.

They don't have to be expensive if you're handy - dh got the shed basis for his from FB marketplace for free.

God, some of the responses on this thread drove me up the wall. It's absolutely batshit what people will do to accommodate SDC at no matter what cost.

OP is supporting everyone financially, including SD's mum!

OP needs to keep her job and that means she needs a space to work effectively.

SD uses the room during non working days only. OP proposes to put a generic desk in there which SD can have use of when she's there. She isn't going to set up SD's room as a home office. Do none of your kids have desks in their room?

OP does not have to spend 18 hours in one room, put her desk in her son's room who lives there full time, whilst SD has a main room elsewhere or try to work in the kitchen whilst there is an empty room in the house that she is paying for.

Those of you suggesting she should are utterly ridiculous, no matter how difficult life is for SD atm.

I just wouldn't have told her tbh and used the room during the week when SD isn't there. I might have bought a cheap second desk so SD wasn't aware it was OP's work desk going in there.

Yep

seems like a whole heap of drama over nothing

But OP won’t be working at the weekend. So the room would be her space for the 2 weekends a month she’s there.

Exactly this. All stress avoided.

I would SD the choice between having the bigger room with your desk or the smaller room with no desk.

I agree. To keep a room pretty much empty for 12 days out of 14 when it could be a separate space to work in is ridiculous to me.

Too right you don’t and you need to pull rank here. It’s very unreasonable of your partner to expect you working from home, daily, to come second to his daughter that’s barely there.

Very high cost of moving
All the stress of moving on top of cancer
All for another 3 bedroom home but smaller overall to save money.

Seems like you’re jumping in to this prematurely

how about the son? People are saying OP should put a desk in his box room instead of SD's mostly empty large room. How's that fair?

Agree with the suggestions of getting a hideaway desk to put in stepdaughter's room. If you need a lot of desk space for paperwork and a proper monitor then something like this would probably be best:
https://www.argos.co.uk/product/7415227
but if you've only really got your laptop in front of you, then one of these is a lot cheaper, and you can keep your stuff in the top compartment, and she can use the whiteboard for reminders and the bottom shelves for storage
https://www.amazon.co.uk/HOMCOM-Computer-Bookshelf-Multifunctional-Floating/dp/B0DPKRZPGZ/
Yes, it would be better if she has a space that is completely her own, but if you can't afford that then it's the sensible compromise given that she's not going to be there most of the time.

Please think really carefully about how much this impacts your SD.
my DD had the same scenario at her dads house and she felt so pushed out and it didn’t feel like home. She didn’t feel like her feelings were taken into account and she was effectively a guest.
this has had a catastrophic affect on her relationship with her dad resulting in her not wanting to stay there.
private space is so incredibly important to a teen girl and your SD already sounds like she’s finding life difficult.
logic supports this option and I get it but honestly, emotions and feeling valued, seen and included are so much more important

We did this and in the box room. Sd and dh shared the space, it had a desk, bed and chest of drawers and she was 14 when we did this. She didn’t need anymore space. Everything that was dhs was cleared into a plastic box just before she arrived and back out when she left. Was never any bother and gave him a space to work

Op, you have a lot of responsibility on your shoulders. Do whatever you can to make it less stressful for yourself. Everyone will adapt. They have to.

One problem with that would be: If the DSD doesn't like the idea of someone just sitting at a desk in her room while she's not staying there, surely she's really not gonna like the thought of someone (her half brother) sleeping and playing in there while she's not there (and having all his stuff in there)!

What is the reasoning for them saying no? If she wants the bigger room then she will have to accommodate the desk. I don't understand the problem if you are going to be in there different times?
Otherwise like others have said she has the small room. I don't see why it's essential DS will need to be in there at 1530, mine are generally in the living room after school.
I worked on the dining table before we moved and it's not ideal when others are in the house, especially a small person.

High earner here and can’t get my head around not having CI cover, especially when me not being able to work would have such a seismic shift in family circumstances

Murphy bed in SD’s room for her- so her things can be ‘opened up’ when she is there.

Plus- a fold down desk, maybe one with artwork of her choice on the decorative side.

That way you can turn it into an office when she’s not there, but back into a bedroom when she is.
Make it so her things can stay untouched but be hidden when she isn’t there.

Why should she muck around with a rickety folding desk when she is paying to keep the whole thing going? I don't believe in keeping children ignorant of financial matters. The stepdaughter has to understand that they are making sacrifices with less money coming in and part of it is OP will use a desk in her room when she is not there. In fact, both my children had desks in their rooms growing up for homework and stuff.

Logically and realistically we all know that DSDs should double up as an office workspace.
You need a quiet, clear area to work and to earn money to keep a roof over everyone's head ffs. But, this is MN and stepmums always get an absolute slaying for even slightly suggesting something reasonable....
There is absolutely no logic in keeping one room exclusive for 4 nights use a month!
I'm sorry but she doesn't get a choice. Choose a nice desk, keep VERY limited resources in there but let her have exclusive use for when she stays over. Its not like you're kicking her out of the room when she's staying over!

It's actually a maximum of 4 days out of 28...

OP already said there's no money for a garden room...

I think no need as dsd needs a desk too.

again op should just not discuss her working set up with dsd at all and she’ll probably forget all about it. It’s none of her business really what happens in the room when she’s not there as long as none of her private things are touched or moved.

I'd look for a portable folding desk and set it up on Monday put it away on Fridays so it's not a permanent fixture, a complaint pain in the ass but it is what it is.