Hey mamas!

Our 3rd is due April 1st and we currently live in a 3 bedroom house. We are planning on having our 3 year old daughter and 20 month son share a room for the next year. I plan to make this change in March so we have roughly a month of transition time before we have a newborn keeping us up all night. This will be a big change for both kids but a huge transition for my son who will not only be switching rooms but also moving to a big boy bed. We're going to let him pick some fun sheets and "boy" up our daughter's room a bit so it feels more like his but I'm still nervous about them keeping each other up at night or my 3 year old understanding its not just her room anymore. Do any of you have room sharing experience? Any tips to make this go as smoothly as possible? Thanks everyone!