My sil on DH's side has an adult 20 year old daughter, our neice. We used to be close to her but for the last 5 years where she has been addicted to coke, unable to hold a job down, been violent, stolen. Her mum (sil) has kicked her out numerous times and she has stayed with friends. She has now ran out of friends and is out of chances with sil as her younger children are all frightened of her.
A few months ago DH neice turned up at mine. I let her in not realising she was drunk/high and she was so over the top screaming and starting chasing my kids. I had her leave but she kept banging on the door and screaming. My children were terrified and now panic at the thought of seeing her. The eldest point blank refuses to ever see her again (age 10). I agree with this and don't want her near my home or family right now.
So now she is living with OAP in laws with no job, no friends, no money, nowhere to go. She sponges off them, manipulates them... Sil refuses to discuss her and dh and I are at a complete loss how to help, we are really worried for DH parents as they, even after everything, see only the good in their granddaughter and think sil is a monster for throwing her out and us unreasonable for not wanting to help her yet again.
I fear they will be taken advantage of, or driven to ill health. They are already unwell and vulnerable. What can I do??