Linda,
Sadly, this sort of thing happens with severely abused kids. They're not exactly sure why it happens, they just know it does. For some unusual reason it seems to be bred into our genetic code to have our bio parents approval, whether they are normal good parents or complete and utter monsters. I'm guessing at some point in human history, that was a survival mechanism.....if a child craved parental approval, odds are high they'd learn the skills the parent taught them and would also be able to survive.
And you have to take into consideration that the Tweedles had had not only several years of very severe abuse on all levels, but brainwashing to believe that was perfectly normal as well.......and done that early, it is an enormous task to learn to throw that off.
I'm going to venture to guess that KT most likely hunted online for her biomonster out of morbid curiosity. It's not hard to find someone that way. Takes some time and energy, but not hard at all. Wouldn't surprise me if she'd found her at some point back when you noticed her behavior take a nose dive. The draw to biomonster is not only that inbred need for approval, but the possibility of freedom from rules ect as well. KT being young, naive, and inexperienced wants/needs to believe biomonster has changed and can love her the way you do. Unfortunately, biomonster has not changed and KT, ready or not, is about to get a mega life lesson smacked upside her head.
Personally? I hope they will commit her to prevent her from hurting herself this way.......taking the risk of distroying herself this way. Because honestly? Biomonster didn't just step into the picture after so many years to play Mommy. She's got a plan up her sleeve.
But sadly, there is only one way KT can learn this lesson, that monsters never stop being monsters, and that is by finding it out herself. And when that lesson hits her, everything you taught her will snap in her head.....your endless love, your selflessness, your giving generous heart, the battle you've waged for them all these years.....and hopefully, at that moment she will have no trouble seeing who her real parent is and making the right choice.
That inbred need for parental approval nearly drove me insane (you just don't get real approval from an abusive paranoid schizo) until I realized that my "mother" wasn't biomom. My "mother" was my grandma and I had always had her approval and her love. That was my turn around point, and I never looked back. I have a relationship with my Mom, but it is not a mother daughter relationship really, we're just friends and I can accept her for the person she is while keeping my boundaries firmly in place.
Even so, I realize this has got to be the hardest thing in the world for you to live through and watch. A literal train wreck waiting to happen. I'm praying super hard for you and the Tweedles every day. You're all in my thoughts often.
(((((hugs))))))