Kelebek, I don't think the same room will work - DD often cries as she is going to sleep and now with the massive screaming fits when she wakes there is no way that DS could sleep through that. DS also wakes several times and has the odd tantrum and won't resettle which would just wake DD up (if she was actually asleep!).

I think we need some sort of professional help with regards to her sleep but I don't know where to go. I gave her phenergan for 5 nights to break the screaming cycle (advice from health nurse) but as soon as she was off it she is back to the same. I don't know what to do with her. DH got up at 2am to save a screaming fit, we thought maybe she would fall asleep in front of the telly but no, she stayed up for a couple of hours then had an overtired screaming meltdown for half an hour or so and finally went to sleep on the couch at about 5am.
DH has to work, he can't be getting up at 2am to deal with her every day. It also makes her a horrible kid to deal with during the day. I am not liking her much at the moment.