Erinaz
its very easy to manipulate people threatening to kill yourself at 15
Feeling/ threatening or attempting suicide is considered a serious cry for help, and it is the idea that somehow she is being 'manipulative' rather than feeling utterly desperate is a very dangerous view to take as an adult and I assume you are in no way a professional. It is in fact a pretty sure fire way of things escalating and ending very badly for the child, as they become increasingly more desperate and unheard.
Adults should always take suicide attempts/thoughts seriously.
It should never be dismissed as manipulation. Who are you to decide whether she will go ahead or not? Or what the motivations are and the cause? Your very poor judgement and advice on here could cost the life of a child.
If any child has got to the point where they are weaponising suicide they are already in crisis. Children do not self harm for 'attention' or to manipulate others to get what they want to this degree, self harming is a very painful, direct and public way of showing absolute distress. Often deep distress and needs treatment, a mental health team and many other agencies that can offer help and support to the child, and family.
Your views seem locked in an age where children's feelings and emotions were largely irrelevant and ignored, in today's world when the pandemic has ruined the mental health of so many young people you are indeed putting children in a very very dangerous position by dismissing the very real risks here. It is dreadful advice and I hope you can live with the consequences.
Op whatever your dd's reasons, take it seriously. Listen, get as much support as you can, even if you have to pay for it (The wait is not so long privately, and apps are still prioritised by need - so do tell them your dd's situation)
It is not good enough to tell a mother to walk away from a desperate child in such dire mental health, by all means parents should get support and help, and counselling, but heavens sake we are talking about a child in crisis here, to me she could be at risk from her violent and abusive father as well as the other issues, the distress signals could not be louder. Do what you can op. That is all any of us can do 