Oh wow congrats! dont't know if you remember but we were in the same belly buddies group!! I personally would puyt them in seperate rooms, our oldest 2 share a room now and we have 3.5month old twins that share a room so I think room sharing is a great idea but for a newborn and toddler i think if you have the option not to share i would take that option., just for ease with day sleeps, baby being asleep and toddler wanting things out of room etc etc