More bedroom advice please

[MamainDenmark]

We live in Copenhagen, Denmark where property price is high and space at a premium. Currently my son (age 8) and my husband's 12 yr old twins (a boy and a girl) all share one big room. Not ideal but we manage.
We soon need to move house and are hoping to be able to buy a place. We would like all 3 children to have their own room but a 4-bed house is going to be hard to find. My son lives with us full-time and the twins half-half with their mum.
In my mind, it's always been a given that my son would be given priority for a larger room in any new house.. he has more toys, stuff etc and it's his only home. I've just discovered that my husband feels really strongly that the children must all have the same amount of space, even though two of those rooms will be use only 50% of the time. He thinks the time distribution is irrelevant.
Any thoughts/ advice? We're still in the realm of theory but I'm shocked to find out he thinks I'm being unreasonable...am I?

Not unreasonable. Presumably the twins will only have half their toys there so need less room.

I'm with your husband on this, you should try to treat all the children equally. If that's not possible, then the boys might have to share when the twins are there, so your son should have a bigger room because he will have to share it half the time. The girl should have her own room when she is there. The twins should not be penalised because your son does not spend time at his fathers, or have I misunderstood and the children all have the same father?

Money only goes so far. Ideally, if you can afford a four bedroom house which has equally sized rooms for all of you then that’s fabulous. The End.

However, as you have said, you feel the ideal will be hard to find.

I would suggest this alternative course of action instead. That you go along with his wishes and agree because at the moment you are arguing of an imaginary ideal and not what is available to you in reality. So he’ll have to find this ideal house and also be able to afford it. And that is when the real conversation starts because at the moment it’s all on a whim of ‘I want’. We all want things but unless you have untold amounts of money, he’ll have to compromise and that will no doubt come down to the size and quantity of rooms.

My son's biological father has never chosen to be involved in his life so him spending time with anyone except us isn't an option.

Room size should be organised by who spends the most time there in my opinion.
In our house (moving in January) it will be like this
Master bedroom - ours (here everyday)
Bedroom 2 - my DD’s (here everyday)
Bedroom 3 - my DS’s (here 23-24 days a month)
Bedroom 4 - my two DSDs (here 4 days a month)

I think it’s the fairest way

For me it would be largest room for you and OH, next largest shared by the two boys, girl has her own room

I think you need to find the house first and then sort out rooms. His children need decent sized rooms as they are there half the time.
Your son having a huge room and the twins having box rooms - not OK.
Your son having a slightly bigger room ok as long as the other two are in nice rooms.
But there will be other considerations - one of the children might like a smaller room with the biggest windows or near the kitchen. There are more to rooms than size, likewise a small loft conversion might be viewed as cool or private by one of the children to make up for a small size.
Table the argument, look for places you both like and take it from there.

I think if you find a 4 bedroom house and one of the rooms happens to be bigger then yes, your son should have the bigger room. It's only logical as he has the most stuff. However, if you find a 3 bed house then the girl should get the private room and the two boys should share, especially now that the twins are puberty age. This might be the best option for you if you can't afford a four bed.

You guys get the largest room to share as you are there all the time. The boys share the next largest room. The girl gets the smallest room on her own.

The boys stuff is organised so your son doesn't monopolise the entire space.

If the boys don't like sharing tough.

🙄