So I just had a conversation last night over dinner, my SO brought up the talk that he had with his daughter (12) when she was visiting last week.
She had been in the bathroom texting again. He called her out on it by texting her and asking her what she was doing in there? I told him to go stand by the door so that she would have to talk to him when she came out but he didn't.
Instead when she came out of the bathroom, she made a beeline out the side door into the backyard.
Not addressing us at all. We were at a friend's house but still, she had to practically walk by us to get outside.

She did respond to my SO by text to say that she was in the restroom. As if he didn't know that already.

He followed her outside and asked her about the texting in the bathroom at which point she got defensive toward him.
She even walked off from him at one point. He told her to get her butt back over to where he was. I think she was most likely embarrassed and shocked. When my SO raises his voice.. he raises it.
She then dumped a load of crap on him.
Asking why did he think he had to tell her she was HIS blood daughter when she was 5? Who tells a 5 year old that kind of thing? All he did was hurt her and her mom and her step daddy.
There was more crap about why he was always upsetting her mom and how her mom vents to her about stuff bc she's really upset.
Basically, my guess is this... the kid overheard someone at a recent get together have a good ol' long talk about my SO and his parenting mistakes or their perceived mistakes.
There is no way this kid....who is socially behind every 12 year old I know would remember crap from when she was 5!!
Her mom brought this up along with all the other bs she was spouting off.

I told my SO that by even discussing anything that was not what the situation was about was letting her manipulate the situation.
She got what she wanted. A diversion from the texting issue.
I told my SO, you keep playing into it and eventually I think you just deserve it. If you keep letting it happen, keep complaining about it.. then it's just as much your fault bc you don't address the real problem or situation.
You call her to the carpet then you let her turn it around to where you are having to answer for your behavior?
NO. NO. NO.
I told him to document exactly what was said and the date.
Then send his baby momma a text detailing the conversation and demand an explanation of why this stuff is being told to his daughter?
Easy enough. He said she might not respond. I said oh, she'll respond. She's used to having the upper hand. She'll try to call. You just don't answer her and be sure you text her to say that you need the response in writing.
He said that she'll see that as hostile behavior. I just said really? And what she's done to you is not hostile? Just bc she wears a smile when you're there doesn't mean she's not hostile toward you, doofus!
She's stabbing you in the back any which way she can. Now she alienating you outright!!
ugh. All I got to say is that I'm glad when she calls and cancels weekends or trades dates. More time for me to relax and work on our house without interruptions!