My teenager's biological father has a daughter in her late twenties. My daughter doesn't see her biological father because he was a danger to her (he physically abused her, violent man and has been to prison). However I always encouraged his daughter to have a relationship with mine. She wasn't right as a child, she set fires and would manipulate adults by making things up. But she was just a child at the time and I felt so heart sorry for her and I hoped having a stable adult in her life would help. Her mother and father couldn't be bothered with her and I put her behaviour down to the craving for attention of an extremely unhappy child. The relationship between her and her mum broke down and she went to live with a relative at which point she stopped coming to see us. When that living arrangement broke down, she went to foster care and was promptly handed back as the very experienced foster parents couldn't cope with her. I did ask if she could come to me before she went onto care but wasn't allowed as I was neither a direct relative or registered foster.
I've seen her a few times as an adult for brief periods and again encouraged her to build a relationship with my daughter. She chose not to. I've not seen her for at least 8 years now but I've heard plenty from others. It seems she's even more chaotic as an adult.
She's now found my daughter on social media and sent her a DM asking to meet up. My daughter showed it to me. Within that DM she's made up a pack of lies saying she's tried to see her but I've stopped her. The DM is all about what she wants, at no stage does she ask my daughter how she feels or what she wants.
I've heard that this girl is into recreational drugs, constantly mooching for cash to feed her habit, has her flat often filled with all kinds of colourful characters. I'm also aware that she seriously disfigured a supposed friend with a weapon. This I know to be true because she pleaded guilty in court to it. So not the type of person I want around my teenager who herself has been mentally fragile, and is studying for highers.
I'm really conflicted between minding my own business (my daughter is 16) and protecting my child by discouraging contact but that carries a risk my daughter may then go behind my back and do it anyway. My daughter likes the novelty aspect of having a big sister and flits between wanting to see her and not.
I also have a toddler to consider so if she does meet up and big sister rubs off on her, it's not just me this affects.
I'd appreciate any advice or views. Thank you.