We co-sleep in our house. We have a king-sized bed in our bedroom with a crib-turned-co-sleeper (by taking one side off the crib) bumpered up against it. Tess sleeps in the co-sleeper, and by early morning she will travel into our bed to nurse. Jack sleeps downstairs in a bedroom he shares with Kain, but by morning he has also traveled into our bed and snuggles up between me and John. Now that we have another baby coming, we have to start thinking about how to manage our sleeping situation. Frankly, my preference would be to get my hippy on and throw down a bunch of mattresses on the floor. Groovy. But I don't think my husband will go for that.
I'm thinking of putting a toddler bed in our bedroom and trying to get Jack to sleep in that when he comes upstairs. Then Tess can sleep between John and I and the baby can be in the co-sleeper. But honestly, most of the time we don't even wake up when he comes into our bed. And he's not really capable of understanding what we want him to do if we discuss it in advance. If we do wake up during the night and send him to the toddler bed, he is likely to start crying and wake up Tess. He will fight it hard, because he fights all change hard and gets very upset when things aren't like they are "supposed" to be.
Another option is to wait until closer to time and train Tess to sleep in the toddler bed. This may actually be easier. Even though Tess is younger, she is more flexible and a better sleeper in general.
Or we can do both...make up some kind of bed for Jack on the floor and try to get him to eventually reach the point of going there when he comes upstairs, and then also put the toddler bed upstairs for Tess and work on training her to sleep there.
Or we could go ahead and move Tess into the bedroom with Maria. The difficulty there is that they have very different bedtimes and I'm not sure how Tess would sleep through Maria settling down for the night.
Anyway...if you've made it this far, thanks for reading my rambling, barely coherent thoughts on the subject!