M.
I would say that at this age it is ok to let them sleep wherever they want. My daughter has reflux and she would not lay down to sleep for many months (she is now six months old and I just took the wedge out of her crib). She slept in her bouncy a lot and then I moved her to a moses basket. I also slept her on her side because for a long time she hated sleeping on her back (I think because of the reflux). I hate to say it but at this age, I think the norm is for babies not to sleep great. You need to do what is best for you, they are too young to develop a pattern quite yet, so put them where they and you can sleep.