Please get your relative help however and whenever you can. It sounds like she is suffering from chronic depression and is reaching out (only to the wrong people). These are all signs and symptoms of depression. In addition, depression can be found in families. She has a very profound genetic history.
If she is far away it makes it very challenging and your only way to take the right steps is through the parents. I know you are scared that you could make things worse communication wise but this is very important. Try to find the person who is responsible for her and have them drag her if they have to to counseling. Also find a support group for her and her guardian. This takes education and outreach. Have her find other children/teens that have depression. You may also encourage the family to get her a mentor that she is more anxious to share her inner thoughts. It would be great to find her a mentor that shares her creativity. All of this can be found online or through putting in time and effort so encourage them to do so. Places like the Alliance for the Mentally Ill can also offer help but they are here - I don't know about your town. Keep communication open and offer these up but if they are resistant than they are not ready to address this