I urgently need some advice on how to deal with my partners 16 year old daughter. I don't know how to deal with her but feel like I should. AIBU or is this impossible? She can be a really lovely, sweet girl. She is very young for her age, quite naive and suffers from severe anxiety and depression. Her mental health problems have been severe for the last 12 months, prior to that she was quite anxious and highly strung but over the last year she has deteriorated. She self harms occasionally and is being treated by camhs. (Counselling, psychotherapy and medication). She stays with us one night a week and is usually much better than when at home (no self harm, no meltdowns etc) but is often anxious and unable to join in day to day activities and often crashes when she gets home, I think due to the stress of holding it together at hours. I am very sympathetic to her problems and would like to offer her support, but am finding it really hard not to get frustrated with her. I have never suffered from depression or anxiety so am struggling to understand how she feels. On the surface her behaviour can often seem very manipulative and it often comes across that she makes her own life difficult. I KNOW this is not the case but am finding it really hard to understand some of the things she does. When either my partner or I try to talk to her about her issues, not to pry but to understand, she gets very upset, defensive and often then complains to her mum that we have been upsetting her. We then get world war 3 from her mum and then missed visits etc. It feels like I don't understand but I'm not allowed to speak to her to try and it's making doing anything with her extremely difficult. Any ideas as to what I can do to be more supportive of her?