Is it just me, or does it seem odd that Camille didn't figure this out sooner, unless she was blocking it out (who wants to believe their mother is a killer)? The Sixth Sense came out a few years after Marion's death, and I felt at the time like EVERYONE saw that movie, especially after it was nominated for an Academy award. Spoilers if you haven't seen it, but
Anyway, the part of this that is so confusing is that for the most part Amma seems ok. I would think she'd be a lot more sickly/weak, unless Adora learned from the gossip the first time around that she had to spread out the poison sessions.
I wonder if what Jackie was saying about how it's just easier to go along with things, is that Marion knew what was happening to her but didn't have a strong enough will to fight it.
So for the other girls? Yeah it was probably Amma (anger at losing her mother's attention) or Amma's father, perhaps he thought this would take up Adora's attention and put a pause on what she's doing to Amma.
I also wonder if Camille killed her roommate and blocked it out, thinking she was saving her from more pain later, or some weird learned behavior.
Finally, I just want to say that I love that Camille unwittingly survived Adora by just wanting her to go away when she would try to care for her. Maybe she subconsciously knew? I would have thought she would love some (seemingly) positive attention from the woman.