I have 3 1/2 year old and 2 year old daughters who share a room. We added a baby boy to the mix last year. We have found it best to just work the new baby into our existing schedule. I understand about being nervous that the newborn will wake up your daughter, but she will get used to the noise. Both my daughters would wake up with my son being a newborn, but since they were in their cribs, in their room and it was the middle of the night, they would go back to sleep. I guess your daughter must be able to get out of her room, huh? First, I would put her rail back on so she cannot get out of her bed or room. Then I would probably turn up the monitor in your son's room so that at the first sounds of his stirring, you can wake up and go to feed him. I did this for the simple reason that I had to make a bottle before getting him and that alone took a minute or two. Then I would take him to another room to feed him further away from my girls' room. If needed and you are comfortable with it, go ahead and move him into your room until he is on a good schedule. I personally don't care for this since I find that having them in my room makes me wake or hear EVERY little noise and I am unable to get any rest even for an hour or two. It may be also that your daughter is adjusting to the new baby and that will take some time and working through teaching her that she needs to sleep when it is time to sleep and stay in her room. Hang in there! You can do it!