My niece has decided she doesn't want to be in touch with either of her parents (they are divorced) but she's in touch with her 3 siblings and has responded to me when I emailed her. Her parents don't know where she's living or what she's doing, and they don't want to put their other kids in the middle of their (bad) relationship with this daughter. All 4 are in their late teens and early 20s, and the daughter I'm concerned about (who is refusing contact with her parents) has been diagnosed bipolar and also has some physical problems (rheumatoid arthritis and asthma). We don't know if she is keeping up with her bipolar meds. What steps can/should the parents take in this situation. This daughter is 23. The doctor she was seeing has told the parents that he is not permitted to give them any information about whether he is treating their daughter.
This confirms what I thought: since she's not a minor she can make her own decisions (whatever the consequences). Really appreciate the feedback, and your time.