We still have no idea how Sara ended up in that crazy "A" dollhouse. What does she have to do with all this? Could she have merely been a decoy?
Last time Red Coat was around, she had long blonde hair. But this time around, we can't see any hair at all. And, hey, who just cut all her hair off? Sara.
It's all too convenient, isn't it? Sara's in the dollhouse, and then she really moves in on Emily. Once she vacates Emily's place and goes to live with another friend, she falls off the map. Which, oddly, is right when Red Coat comes back. Coincidence? Maybe not.
Why She's Not Red Coat:
Sorry guys, but Sara seems clueless. Like, we have a hard time believing she's capable of harming anyone. She can't even take care of herself.
Remember that terrifying video of "A" holding a knife to Sara while she's sleeping? It would be weird it they both teamed up after that.
Assuming Sara really was in captivity all that time, there's no way she could have been one of the Red Coats causing chaos before. And it really seems like she was in the dollhouse for a while. She's a mess.