I have came up with a theory about Jessica DiLaurentis. So I believe Jessica is Bethany Youngs' mother. This is because she had an affair with Peter Hastings (Spencer's dad) and Bethany's dad. This would explain why Bethany looks like Alison, the Radley visits, same two yellow dresses. But Jessica has Bethany call her "Aunt Jessie" to for a cover up. I also believe Jessica DiLaurentis and Marion Cavanaugh are sisters, because of their facial features are so much alike. This would also explain the Radley visits, But it would also explain Jessica being on the board at Radley. Possibly to keep an eye on both Marion and Bethany, and so family secrets don't get out. I also believe Bethany is the one who killed Marion at Radley, Jessica found out and threatened to tell the truth. This would explain Bethany's aggressive drawings of Jessica. Also Dr. Palmer told Marion to " stay away from that blonde girl", I think he is referring to Bethany. Maybe he knew something about Bethany wanting to kill Marion?