I swear it never ends with DD2

I mentioned last week in a post about her moodiness and inability to sleep. Many of you suggested she was overtired which I am sure is the case but she claims she can't sleep and gives up a super DUPER hard time at bed time which gets everyone all out of sorts. We have tried MANY things - positive reinforcement, negative, the gentle approach, the tough approach, leaving her be, etc. I don't know what else to do.

Last night she just went crazy. She decided she wanted to sleep with her sis on the top bunk and A) we could not allow that and B) DD1 didn't even want her there. She just sat there and sobbed and refused to move. I was finally able to coax her down and laid in her bed with her. She was crying loudly the entire time, like hysterical, then started saying she wanted a pacifier! I was shocked and confused. I told her that she gave them up a long time ago (when she was 4) and didn't need them, she was a big girl, that I would lay with her and stroke her hair, back, whatever. In desperation told her to suck her pinky or thumb. I felt really sorry for her that she obviously wanted some type of comfort I was not providing.

She eventually came into the living room and hung out with DH and I and we let her have something to eat. We usually don't but these seemed like extreme times and we bent the rules. DH walked her back to bed and she seemed ok but not tired. It was 10:30! She hung out in her bed with her lantern on for a bit and eventually did go to sleep.

Today I asked her why she was so upset and why she felt like she needed a paci. She couldn't really answer but said she wants to use one tonight! I kind of thought that was a one time thing. Now I am afraid it will become a whole battle. DD3 still has pacis so she sees them all over. I am not really sure what to do anymore.

What is the deal here? Is she regressing? Just wanting comfort? She has had trouble sleeping since she gave up the pacis last year. I almost wish I COULD give them back but it's probably not a great idea. Bedtime has just turned into such a nightmare and DH and I are totally at the end of our ropes.

I know someone mentioned the book "sleepless in America" which I plan to get at the library soon. Anyone have any other ideas here?