How Do I Put My Two Kids in the Same Room?

Drop the crib (why would she smother her sister) get a set of bunkbeds or a trundle bed that has the mattress that pulls out. she is at the age where potty training will start soon might as well start them out the way they will be sleeping. I would go with the bunkbeds. you can get a mesh siderail for the lower bunk

We built a short wall in their room so that they each had their own space as well as shared space. I know that building a wall isn't always an option, but you should be able to arange the funiture to allow a little privacy for each.

You talk with them and explain the situation.
Talk about it, like they are a "team".
Not the older being better or the younger one being better or one being more bossy over the other.
Explain it to them and let them ask anything they want about the arrangement.
Tell them, your hopes about it.
Then, organize the room to accommodate both of them. Fairly.
DO NOT, give the 4 year old, the 'task' of minding his/her younger sibling. This is not his/her responsibility. Or they may resent it.

And yes, 4 year olds, are not all grown up in terms of problem-solving or impulse control or maturity or coping-skills or deductive reasoning. So have a baby monitor in their room... so you can hear them, too.
You will still have to run interference and supervise when needed.

Or, you put their mattresses, on the floor.

Or have a partition or folding screen in between them.
Unless they will push it over.

And if they have different sleep times/nap times.... you will have to toggle that. Because, there is a big difference, developmentally, between a 2 year old and a 4 year old.

And hopefully they get along. But you can't predict that.
Me: I shared a room with my sibling when younger. It was awful. I HATED it. Why? Because my older sibling, was a controlling/fussy/manipulative.... kid. And she only did it, when my parents, weren't looking.
So eventually, I got my own room.
It was needed.

And you need to also factor in, that they will each have their own individual age-related phases.

We always had two to a room. Well, until the last ones were left and the others gone and then they got their own room. When little they all shared and it was never a real problem. It's all in how you act about it and how you present it and let them know what you expect from then so there are less problems. If and when there is an issue just deal with it. They should be closer sharing a room and won't mind at all. Be sure to have a place for the older child to keep her things so the little one isn't in her things to teach respect for each others belongings though.

Your attitude will affect your childrens' attitudes. So make sure they know you think it's great that they GET (not have) to share a room.

Expect for it to take a while before they start falling to sleep on time. You could try earlier bedtimes (but not necessarily the same bedtime) for both for a while, because when they're together they're going to do some talking and even some playing!

My children had to share rooms (we had two girls and two boys), and they all lived to tell about it. They weren't happy about it every minute! But once they were in college they all said the dorm adjustment was rather easy - they were way ahead of their friends who had never had to learn to share space before.

I don't know how it will work for us either (mine are almost 3 and 5.5). I'm sure there will be an adjustment. But please don't put them in bunk beds yet! I doubt your 2 year old is safe climbing and playing on the top bunk so why risk it. My husband broke his collar bone falling off a bunk bed as a child (he was 8). We have beds that can be bunk beds (later) or twin beds.

Don't make it out to be a bad thing. My sister and I had always shared a room. It wasn't until she became a teen that it became a problem (she is 3 years older). I think for young kids it will help them feel more secure knowing their sibling is there. My step daughter has her own room here at our house but likes to sleep on the top bunk in my daughter’s room (they are 7.5 years apart and very close). They both sleep better knowing the other is there.

We just billed it as so special. It must have worked because our daughter is jealous that she has to sleep in her own room. She wants company. Your kids are too little for bunk beds, though. We did captain's beds for our boys. They have an average size room, but it works because we don't need a dresser in there. They have a few minutes to decompress, but if they're still talking after about 15 minutes, we remind them it's time to go to sleep. The more disciplined you are about bedtime, the easier it will be. Hope the move goes smoothly!

Some of my kids always grew up sharing a room, I have 6, 2 girls and 4 boys. Because my girls are so close in age (14 and 16) they have always shared a room, and my two twin sons that are 13 has always shared a room, but my 11 year old and 5 year old has always gotten their own rooms because of the age difference, lucky them! Just remind them that your short on space, and GET to share a room, act as if it's really cool that they get to share rooms with eachother, and that fact that they are 2 and 4 they probally dont mind a ton, but my teenagers sharing a room is alway interesting! ahha. Just act as if nothings really new, and just do regular bed time rituals :)
Good Luck!!