To want SD’s room to be multifunctional?

I don't think the solution is completely unacceptable but I think the OP could have phrased it much more delicately. 13 year old girls who live between two homes can be very unsettled. She is still a child and has at least 5 more years of living between two homes. I can understand why she and her father want her to feel that your home is also her home and that she is not a 'guest ' when she is with you. As soon as you use terms like 'multifunctional' you are sending a clear message that you do not consider the SD as a full member of the family. I think a desk in your bedroom would be a better option.

How long have you and DP been together, OP?

Who owns the house you currently live in?

Based on your situation - ill DP, can't afford current house, have to downsize, you have to wfh full-time, SD there every other weekend at most - then compromises have to be made.

It makes no sense to keep a bedroom empty 86% of the time when it is the best solution to use it as your work space Mon-Fri.

SD could choose the decor of the room, so it feels more hers...

I would stick to your guns re this, OP, and DP can either agree, or you can each find something that works for each of you. (How much equity have you got?).[

When ex-DH and I split up, I could only afford a smallish two bedroom flat. DS was 17 so was pretty much doing his own thing anyway but I still wanted a space for him to stay over when he wanted to. I bought a folding desk and small office chair which could be put away when he stayed the night. It worked absolutely fine for both of us.

Your DP is being very unreasonable. It’s utterly ridiculous to have a room unused for all bar four days a month when you need somewhere quiet to work. What would happen if you lost your job because you were unable to concentrate properly whilst working in a kitchen with all the usual family hustle and bustle going on. Then you’d all be fucked.

I never understand ppl who expect a bedroom to sit empty for use one or two nights a month.
Boxroom with desk, DP can always get a house himself to accomodate his DD

Why should she. she is the breadwinner and making it work within their budget. You think getting a bigger house vs a room sitting empty in a smaller and affordable place is the smartest idea?
or is it just because it’s a step parent ?

stuff that op, she doesn’t get to decide and neither does your dh. You using it during the week affects NO ONE during the week. Not one person. Yet using another room in the house makes your work situation, the money funding everyone difficult

We downsized a couple of years ago and I worked from dd's room when she was at Uni. It's a poor use of less space to have a room practically unused.

How old is she?

I think it’s reasonable to have a desk in there if she’s only around at weekends and you can clear away your work stuff. If she was around in the week it would be different.

Currently I use a desk in DS’ room to work in. He has a double bed and DH’s office has an ikea daybed. When guests come, DS moves into the office room. Not ideal but we don’t live in a mansion so there we go!

Partition off a cubicle in whichever is the biggest room.

It just doesn’t work any other way. I wouldn’t work at the kitchen table. I’d look for a lockable cabinet and tell sd it really is her bedroom, I only use the desk, but if she feels better about it she can have a lockable cabinet for her special things.

I don’t understand why it’s such a big issue? All you’re doing is putting a desk in there…?! Seems sensible to me.

Yep. I'd stand my ground on this one. Set the room up as SD's bedroom with desk for her homework. Then use desk during the week and remove the laptop and any other work stuff when she's there. You could have a lockable drawer in the desk for any small items but if you didn't she wouldn't even be able to tell that you use it when she's not there.
They are being totally unreasonable.

Unfortunately for them, as DP is not contributing they don't get the final say.
If you hadn't told her you were working from that room during the week it is unlikely she would have even known anyway, what are there actual objections to you working from there?

@SamphireSupper how about a table that folds up against the wall?

Tough tits really. Your work is paying for that house. If they don't like it, they can live elsewhere. Sounds like the most practical solution. She won't even know you're there during the week, will she? Just find somewhere else to keep your paperwork when she's back using the room. From a confidentiality perspective, you might need to do that anyway.

We do this with my eldest when he is home from uni. My study becomes his bedroom.

She’s there literally two weekends a month eoth no stuff. She gets to stay In your office

Is there not an option to have some other kind of surface in there that you could work on which she could use as eg a makeup table, and you just take your chair in when she's isn't there and move it out when she is? Bit of a faff but perhaps a reasonable compromise? What is her objection to the desk- that she doesn't want you in her space, or doesn't want a desk?

I think I’d be buying a house without your DP in it at all, he is being very unreasonable.

Your SD visits every other weekend and wants the second largest bedroom kept for her sole use? That’s unreasonable.

so they are objecting that you use a desk in her room during the time she's not there? It's not a shrine. Is her room currently forbidden territory for you? Tell them the room will have a desk, for SD during weekends but you will use it during the week, end of discussion.

Just make it tidy at the end of the week and they won’t even know 😅

From experience of a similar scenario, I suspect your DP does not want to move. He’s using SD as an excuse to drag his feet.

If you absolutely have to move, he and SD need to compromise. This is going to sound harsh but without compromise you don’t have a partner - you have someone that’s exploiting you.

Of course it’s fine - it is the only sensible solution. She will have her room to herself when she’s there and i assume that apart from your desk the room will have her choice of duvet cover and decoration and the bits and pieces she leaves there and her clothes etc.

DS works from DD’s room when she’s at uni. She’s not thrilled but such is life and he doesn’t work there when she’s home. It doesn’t stop it being her room or suggest she’s not welcome it just makes sense

I have my desk in my son’s room - he’s at school whilst I work. Hardly world ending. And at 13 she will use the desk for homework surely?

I would be telling DH he finds a job to suit his medical illness as if he wants to keep a room free do his child you need four bedrooms. Otherwise it will work as you want it

working in the kitchen is not going to work if he and da are around. DS wont understand that he can’t talk or play with you and you will need quiet to work

slabs to keeping a double bed Tough. She gets a large single and you get a desk in there

Sod that your having to downsize so she will have to adapt. Your the breadwinner so you need peace and space to do that. Tell her it's that or the boxroom