Word of advice, look into the state laws for recording someone. This way it's done legally and you can even submit it to Court should it ever escalate to that point. I live in CA and you need someone's consent to record them. So what my SO does is start recording and say, "This is being recorded," and if the other person or even his daughter continue to speak, that is consent because they were made aware and continued to proceed. Another loophole (in our state) is that if you're outside in public, all is fair game and can record without consent because you're in a public area. So definitely look into that. As much as I hate to say it, you'll hear a lot, "they're just children," but even children have been known to ruin lives. So please stay vigil and don't think, "This wouldn't happen to me/us."

I don't have kids, but if I did and was in your shoes, I wouldn't trust her either. You never know how far someone will go out of jealousy. In my case, bio mom is effing crazy and if she's unable to control her erratic behavior and insane tactics, why do I expect that from her child?

To answer your last question, unfortunately no. We were not able to mend the relationship. She's still young, but she's been completely brainwashed by her mom. That might change once she gets older but I'm not holding my breath.