When our DD2 was born, we had TONS of NWings from DD1 (she was 2 years, 4 months when DD2 was born, but the peak of bedtime battles and NWing was at 2.5 years, or when DD2 was 2 months old). It's a major source of stress and a very common cause of NWings for toddlers. (I just wish someone had warned me about that beforehand.
). I was lucky enough that DD1 was still napping solidly, so didn't have the no-nap transition going on at the same time contributing to the OTness. The OT you can manage a bit by ensuring she gets a 12-hour night on days she doesn't nap (though we are in the dropping the nap phase, too, and that in and of itself is causing NWings for DD1). The new baby situation will slowly improve, but what helped us tremendously was making the bedtime wind-down really long and relaxing. Like an hour, including books, massage, storytelling, and music. That helped her wind down enough and also gave her lots of one-on-one attention from us. Things are pretty good now with her night-time sleep, now we just need to sort out her sister....