Addition and Who Sleeps Where Question

Put baby in small room. Each get their own rooms but they can continue to sleep in one room together. It saves in juggling in a year or so.

Okay so the bottom line is, now and in the future, each child WILL have and do have, their own rooms. Right?
Regardless of gender. And regardless of size. Each child does have a room of their own.
BUT if you make one of the rooms, (ie: the smallest one), into something else for some other use (like for a mini office or whatever), then you will only have, 2 bedrooms for the children. And, keep in mind... that once you make a room (ie: the smallest one for example), into another type of room for another type of purpose... THEN, later, WHEN one of the children do need a room of their own... will.... you/your Husband actually and excitedly....WANT to change that smallest room, into a bedroom/room for whichever child? My point is: Typically, ONCE a room is changed into say, a mini-office or a space for an adult/or the parent/or as a guest room... it is hard for that present occupier (of that extra room), to GIVE IT UP. Because in the meantime, that room is thought of, as "his" or "her" room or office or den or man-cave or whatever.
So you need to think about that.

Thus, I would, keep the rooms for the children, so they each can have their own room. Because no matter what, as a child gets older, they WILL want their own room. And need to. And per whatever gender they are. Especially once they hit middle school age. They will want and need their own room.

And meanwhile, if/when your 6 year old daughter wants to sleep with her younger brother or sister, then well, fine. She can do so. She can go to his room, or he to her room, and do that. They can each have their own separate room... but yet still be together if they want. But retain, their own room. And they can camp out in each others room.

And also, just because your 6 year old daughter wants to sleep with her brother (or the baby), it does not mean that they want to. Maybe they, don't want to sleep like that????
Its not up to the 6 year old. But she can camp out with her sibling sometimes, but yet have her own room.
But no matter what, I wouldn't have the baby with the sibling. Baby should be kept by you. Babies wake and the parent has to wake for baby.

Also, even if you have kids that are the same gender, that does not mean they have to or should, share a room. They might not want to, they might not even get along, they might have totally different tastes or ideas about how they want "their" room to be, etc.
So bottom line is: each child should just have their own room. Regardless.

I shared a room with a same gender sibling when I was a kid. I HATED it. It was a personality clash and a clash of morals and behavior and ideas and styles. We were just not able to cohabit the same room, as a personal space. It was not, a peaceful relaxing personal space/bedroom. It was a battle, space.
But outside of that room/our bedroom, well it was better. Because then we did not have to, share everything. etc.

And the other bottom line is:
you are considering making an addition to your home, IN order to add on 2 more bedrooms FOR the children.
So, thus, use the additions of 2 more bedroom, for, the children.
Not it being still, having only 2 bedrooms for 3 children. And then the 3rd smallest one being used as a mini office or guest room or whatever type of room. Use it, as 3 bedrooms, since that is why you are considering making additions to your home.
This conundrum is ALSO BECAUSE, your 6 year old informed you... that SHE wants to sleep with her sibling.
Well, fine. She can sleep with her sibling. But that does not mean she should have a combined bedroom with that sibling. She can, camp out and sleep with that sibling sometimes, but yet still have her own room. She is 6 now. And SOON, she will want/need her own room anyway.
And it does not mean that her sibling will want to sleep with her or share a room with her. Who knows.

Again, KEEP the 3 rooms for each child. So they DO have their own room. You will need it anyway, once they get older. Regardless of gender.
And the kids can pop in and out of each others room and camp out there, if they want to sleep together if/when.
But I would not keep the baby in one of their rooms.
It will be too disruptive and there will be no sleep.

Its not complicated.
Each child will have their own room.
They can still camp out in each others room and sleep with each other IF they want to.
But they will have their own bedroom/their own space/their own personal space. Now and later.

Also, because, if you use that smallest room for something else.... then in the meantime that smallest room will be undoubtedly filled up with other things for other purposes. Then when you do need that room for your child, where will you then put all those things? And, will you even want to give-up that room, for one of the children, later?

everyone should have their own room

My advice is they each get their own room. S.H. gave some valid points, as did others.

My thing is, the baby isn't here, so how can your 6 year old know she wants to sleep with him or her? She may have an idolized idea of what that would be like, don't we all at some point, pre-baby, lol? The reality of hers and the baby's sleep being interrupted or disturbed due to middle of the night feedings and changes, her bedtime and morning routines, her needing her own space soon, etc., would weigh heavily in my decision. She can always put a sleeping bag down in the baby's room on non-school nights and camp out if she chooses.

To ensure that everyone gets to and stays asleep at bedtime and through the night, I'd put each in their own room. It's so much easier to get and keep kids asleep when they're not distracted or awakened by their siblings.

Also, your 6 year old will be is in school and does not need to have her sleep disturbed by an infant waking several times throughout the night.

Your daughter says she is fine sharing with her brother or the baby. Does your son have a preference? Ask him and go from there.

Whatever works for your family - go for it. Personally, I would create a room for each child, then let them sleep where they like (providing they don't interfere with one another's sleep. It may be comforting for them to stay together during the transition of adding a new sibling.

Congrats on your new addition!

I think age matters more than sex when they're little. My son and daughter shared a room and loved it, from preschool through early elementary age. I'm sure neither one of them would have liked sharing with the crying, pooping baby! (She was in the office/guest room for the first few years.) They had bunk beds, each with their own choice of bedding, and the room decor was neutral. I hate "themes" anyway, they outgrow them every six months. I say let them share as long as possible, it's not hard to move things around and adjust later. Use the small room as a playroom or an arts and crafts room, that's what I'd do.

It all would just depend on how it works best. When we had our youngest 11 years ago he was in our room with us even when he went to a crip because he would keep his brother awake at night if we put them together and our room was much bigger. But when he was 2 and oldest was 5 we moved and they shared a room. For years our youngest did not want to sleep in their room alone. He was scared so that may be part of her issue. Yes I have two boys so I don't have to worry about their age or anything like that. But I know I shared a room with both my brothers at different times. And it was not a space issue it was I was scared to sleep in a room alone. I was probably 6ish when I started sleeping in my own room. If she wants to say in the same room as her brother I would say keep them together for a while till the baby get's old enough for a bed. Then maybe your daughter will be ready for her own room or if the baby is a girl you can put them together. You just know you have another room when she's ready. I am one that trys not to force kids to be out of their comfortzone with stuff like that.

My vote is that each child gets their own bedroom. Since your daughter is almost 6 (and looking at your profile, your son is 3), I would guess they aren't on the exact same schedule especially with your daughter being in or starting school.

I would put the older two in each of of the two bigger rooms and the baby in the smaller room. When the baby is not a baby any more, and if the older same sex sibling also wants to share the room, then you can move the youngest in with that child and turn the small room into an office or something.

I'd let the kids lead on this one - they're still young and probably like the security of having a roommate :)

My older two not only share a room, but a bed. We co-slept with both of them for 4 years, so they're used to another warm body next to them. Fine by me; there's no more knees in *my* kidneys! As a kid, I shared a bed with my sister as well because there was no room for 2 beds in our tiny house.

I like Eliza's answer: Set up separate rooms, but let them sleep wherever they want (for now). So, right now you only have 2 rooms (the master & the kids' room)? It's great to plan ahead, but a 2-room addition can take a long time! My dd is 4.5 and has been sleeping in her own room since she was a toddler (more or less)--we did some co-sleeping when she was an infant and shared a room for a few months while we lived with my parents (looking for our new house). We've been in our house for 2 years and she has her own room and sleeps in there 99% of the time. We have extra rooms, so when we have another there will be separate rooms.
I think your kids can have a say in what they want, but you (parents) have to go with what works best for you (and the family as a whole).
Good luck mama!

I would unequivocally put the newborn is his/her OWN room. Regardless of how you pair the others-give the new one his own nursery, with darkening shades, white noise, and a door that shuts!

BTW, I had opposite sex kids share for 4 years they were 7 and 3 when they started, and just separated at 11, and 7.

This happened to me when I was 4 and my brother was 6. We moved to a bigger place and had space.The baby got the small room right next to my parents downstairs. There were 2 bedrooms upstairs, but my brother and I had shared before and I wanted to continue to sleep in the same room. My parents let us sleep in one room with both our beds in there. However, they also set up the other bedroom for me with a bed and all of my toys. That one was "my" room, but I could choose to sleep in the room with my brother if I wanted. I did for a number of months then decided to sleep in my room. It was the perfect solution. Being opposite sexes they wanted us eventually to be in different rooms but were sensitive to my need to do it at my own pace. I remember that I had never slept in a room by myself before and frankly did not want to right away. Fortunately, my brother did not care either way. This solution did involve buying another bed but it worked so well making me comfortable and giving me the choice to transition when I was ready.

until the baby sleeps through the night .. baby needs his own room.. so the older kids are not getting woken up by baby..

once baby sleeps through the night whatever works...

I would make the smallest room a nursery for the newest baby. It will be many years before he/she needs a bigger space. Let the older two have the bigger two rooms. If they want to share for now, that's fine, but lay out a plan for WHO has to move when the time comes to avoid fights. Maybe even write it down and make them sign it (even if your son can't write). That could be a bigger headache when they both want the same room later. If you do end up with an empty bedroom, it could either be a playroom for the kids or just set it up as a guest room with what will be the future furniture for your son or daughter.

ETA: Actually, I think Brooke A's answer is perfect! Give your son and daughter each their own room (the two big ones) but stick an extra bed (bunk beds?) in one so they can share if they want.