I have three or four in the same room and they can all see each other and are all different ages, then I have 1-2 in the adjoining room. But I'm super lucky that I sit in the room and sing a few songs and cover them up a few times and lay them back down and within 10-15 minutes they are all asleep for a couple of hours. It takes practice and patience but if you teach them this is how it's going to be they learn. I'm sure there are children who are so stubborn that I will run into and have problems. I have certainly had screamers for many months in the transition phase but I get them all into this routine eventually. It also helps to wear them out completely all morning so they are exhausted.