How big is your bedroom? We had DS in a single bed on my side of the king bed and DD in the middle. With DH no longer here, DS is refusing to sleep in the single bed and is on DH side. DD is on the single bed (most nights) with a side rail. It may be an option to have a narrow single bed as extra width rather than a side rail on your bed if you have the room. DS2 will either be in a safe sleeper in between DS and I (I don't see him moving out any time soon ) or in the safe sleeper on the single bed if DD decides to migrate back to the middle of the bed.