Need suggestions

Having just found out that I'm pregnant, I'm starting to try to figure out ways to rearrange the way sleep works around here. I want to do it early on, so that my son doesn't feel as though he's been replaced by the baby.

At present, my son and I share a single bed, with my husband on a queen mattress next to us (all on the floor). My son has to sleep against the wall, since he tends to roll until he runs into something. He also needs me to be there to get him to sleep.

Since that could be problem with a new baby, I'd like to try to get him to sleep when daddy or mommy is there. Eventually, I'd also like to have things moved around so that B sleeps with his daddy instead of me.

He's too restless of a sleeper to be near the new baby. If it turns out that I'm carrying twins (which I keep getting feelings of, even though I'm probably wrong : ) he's going to have to sleep on the other side of his daddy.

I'm just not sure the best way to go about changing all of this. Obviously, I want to do it gently and gradually, but I want everything to be sorted at least a few months before the baby comes so that B has lots of time to get used to the new arrangements and doesn't feel as though mommy kicked him out for the new baby.