Far too complex a scenario for me to comment on, plus, I'm not qualified to. What did jump out at me is that you have a Daughter who has ADHD, and who has said that she is planning her own suicide. As an aside, I don't believe for a minute that ADHD would qualify her being accepted by Dignitas. Nevertheless, mental health issues plus suicidal talk is an extremely dangerous combination, and in your shoes, I would certainly be looking to report this to an "appropriate", safeguarding agency. I don't know who this might be. Do Samaritans give advice on situations like this? Could your own G.P. help? Whatever it takes, I'd be looking for some urgent, informed advice here.