J.N.
How about feeding the little one in a place where your daughter can also cuddle with you? There is absolutely nothing wrong with her not falling asleep on her own in her bed. Especially with all the upheaval in her life, your daughter needs a few extra bits of security, and if letting her cuddle with you as you feed the baby, and even fall asleep there (to be moved to her bed afterwards) could give her enough to be able to settle down better.
My husband worked nights when I was preggers with my 2nd, and the first was about 2 1/2. I finally gave up on the bedtime fight and let her sleep with me until the baby was born, then I started putting her back into her bed after she was asleep. It wasn't long after that she was able to go to sleep in her own bed, and now (she's 11) I have a harder time getting her up than putting her to bed! lol .... The point is you don't "spoil" them from sleeping on their own by giving them the extra security they sometimes need :D