Did anyone notice the birthmark?

The first time Maggie walks in the room, there is a mark on her foot. Later when Abigail's father injects her with something, you can see the same mark on her foot too. I think it's really important and I'm amazed they did not mention it in theories I have read. that looks like a birthmark to me and it proves that Maggie and Abigail are related.

My theory is that they are sisters or Maggie is Abigail's mother and both little girl and her father are involved in the cult. that explains Abigail's weird behavior since she is probably brainwashed and drugged by her father. As far as I know, you don't usually inject people in between their toes unless you intend to hide the sign of injection. So the whole story of Abigail being Maggie's mother was to deceive Peter and convince him that Maggie is telling the truth and they almost did it.

The aim of the cult was to make a secret terrorist army like that woman from DoJ told Peter's girlfriend. That's why Maggie tells the members that she is leaving them. She probably plans to go to other parts of the country and fool more people.

I think the point is that even someone like Peter with a Logical mind and a background that makes him hate the cults, can also be fooled by one of them.