Charlotte knew Mary Drake was her real mother. But, according to Jenna, she never met her. So what exactly did she knew about the Drake family ? Was she aware she had a younger sibling ? I believe she did. Also, I think she had to lie during the revelation in 6x10, but these lies had clues on them. Let me explain:
In the episode, she used this lyric "Lord help the mister who comes between me and my sister". She knew Ali was only her cousin, but the whole Charles point was to win Ali's trust and being able to play the victim, so we can believe sister meant Alison and mister meant the Liars. But what if it was a hidden truth ? A teasing that once, a man (AD ?) came between Charlotte and Mary's second child.
Charlotte loved to play, she's not on the girls' side, but she cared about "her dolls". Twisted Charlotte could have let hints that this mister will soon hurt the Liars. If not a hint to the girls, at least one to the audience. Charlotte's story is weird, what was real or false ? but what she said is relevant. During the controversial Marion's murder flashback, Charles and Bethany dialogue about their escape of Radley "Nothing’s more believable than a really good lie. We just need to come up with a great story – something fabulous and devastating at the same time" Fake death sounds like something that could fit their plans. So maybe they did it. If the night Bethany escaped Radley, the plan was to mistake Alison for Bethany and somehow fake her death, Bethany would have been free of Radley for good. Proof, for two years no one seemed to care about her disappearance, till episode 5x05.
Is it possible that Bethany was Charlotte's sister ? Charlotte escaped thanks to Jessica who faked Charles' death. What proof do we have that she really came back to Radley after Charles' funeral ? I mean, why would Wren had to make Cece's visitor pass if Charlotte was still there ? And with Noel's secret, we now know that Charlotte's time in UPenn was relevant. Charlotte never came back, she enjoyed life out of Radley until Noel pushed that girl.
In the beginning of the show, the body found in the DiLaurentis' yard was identified as Alison because of the yellow top, the Alison's bracelet and also with the help of dental records. Someone switched Bethany and Alison dental records. Charlotte said she was A from season 3, so she didn't switch them. Mona hit a blonde girl before she helped Alison to disappear. Mona never buried Bethany, she didn't knew her, she hit her but she was still alive. Melissa buried Bethany but claimed she never saw her face. So who else knew the dead girl was Bethany and needed people to believe Ali was dead. Maybe the same person who gave Bethany the Alison bracelet ? That "famous mister" perhaps ?
In Charlotte's version, crazy Bethany stole Charlotte's clothes. Ok, ok. And it's a pure coincidence that Alison received the yellow top that exact same day ? No way. Charlotte lied, or at the time she was clueless that someone else was involve. A.D. ! Jessica never wanted to buy the top for Ali, someone else let the tops for Ali and Bethany to wear them. Why ? I don't have a clue. In Mona's version, she wanted to scare Alison and later hit somebody she mistook for Ali = no mention of Ali's yellow top. In Charlotte's version, she just followed evil Bethany = again, no mention of Ali's yellow top. The two girls were identical that night for a reason we didn't find yet. Was it Uber A's plan ? If yes, that person needed to be aware of Mona's and Charlotte's intentions for that night. He's the ultimate puppetmaster, he tricked everybody else !
Charlotte said it. Sara was only a decoy, just a decoy, Red Coat's decoy. She needed a decoy the night of the fire at the Lodge. In what other occasions did she use Sara ? None that I saw. Maybe, Sara wasn't Charlotte's Red Coat decoy. I believe there was three Red Coat: Ali, Charlotte, a mystery 3rd one and Sara (decoy of the 3rd ?). At the fire, Charlotte had black hoodie, Sara was the decoy and Alison had her hooded red coat, but firemen found a burned hoodless red coat after the fire. Who wore it ? Sara was a tool, the 3rd Red Coat was the real "friend and ally" and the one who managed to get prom tickets for Charlotte.
Other proof that Uber A was there that night, we never found out who took the picture of Ali and Spencer encounter (picture found in 4x21). The one taken from the second floor of the DiLaurentis house where we saw Alison walking away from Spencer's shadow. They said (by Ezra's journal) Cece witnessed that feud and Jessica paid her to say nothing about it. Another piece of the Charlotte's story that, from now, fit no where.