Therapy shipwrecked our family, suggestions?

A year ago last Nov., a therapist recommended we seek out our adopted dd biological siblings . She came to us when she was two, and maintained contact with her older brother and sister until age 4 when all contact was cut off (not our decision) . Both bio parents were TPR’d ; the older two kids were taken by a family member ; they could not take all three. The youngest was placed in foster care and was adopted by us by age four. We had heard that the other two (her siblings) were eventually reunited with their bio dad when he was released from prison. We never heard from them again. Fast forward 10 years later, our once happy, easy going and well behaved child changed. She became withdrawn, easily angered, depressed , and eventually we had to seek counseling due to suicidal thoughts. Her therapist said she felt that the separation from her bio siblings was the root of her problems. That contact was made a year ago this past Nov. and our family has been shipwrecked ever since. Meeting them led to a one day visit with bio mom and dad who were trying to get back together… And then over the course of 9 mos she became adamant on leaving us to go live with them. So much so, she ran away to them. In the short 4 mos she has been away, she has witnessed many traumatic realities of life with her bios. A suicide attempt, an attempted murder, many conflicts , abandonment again - dad left- and eventually homelessness. There are also strong suspicions of sexual abuse. She was finally found and picked up by police, and transferred to an acute care facility. Due to her mental state, they are transferring her to a residential, long term facility for adolescents. We hope that through all this, somehow? We can heal as a family . My question is, what is the success rate of therapy for kids /teens that have found and reunited with their bios against all advice?? Even now, (but it’s only been a week of short term help) and after all the violence and abuse, she insists “she was happy!” And that all she wants when she’s “done her time” is to be with them again?? They aren’t even living together anymore. I sense that her real motive is to be back with her older, biological brother with whom, I believe what I’ve read called “GSA” , has taken place. We found things on her phone that removed all doubt something unnatural was going on. But charges cannot be pressed as there is no concrete evidence. But again, I’m asking, can a teen that has reconnected in such a way as this, be detoxed from this literally fatal attraction?? Or is it too late now??