First off Cable I am 100% sure Danielle is not Annie. First off because Ben isn't the real dad. Second because she is French. You can't turn someone into someone else. Also brainwashing isn't that easy.

My theory is the same. Accept more detailed. Like she was working with Calvin. That she wanted to get Hurley drunk on Two for the Road. I've watched all episodes with Libby very closely. I say her flashback in dave it looked like she didn't take any pills at all. Also if you watch when she looks scared and when she looks happy it shows alot.