Hugs Arte....
I dont have any advice - I reckon I have given any advice i had a while back, its really tough isnt it...
I did find when J ws born that if N also woke I could get him to lie there until i could deal w him - and the newbown settles were easier than the toddler ones.
Perhaps W is old enough to understand when bub comes he has to stop tantruming? (that kind of discussion works ok with N) - you could use the new baby arrival as an end point for that behaviour.. then maybe A can settle more (like it sounds like she was a few wks back)
A bed in her room?
Only letting DH go in, after a while she may accept if that is the only option

Do you have a plan to stop using the phenergan (or does your doc have an opinion on that?? - does she suffer allergies that are keeping her up??)