Open Eyes - thank you for your response and offering some suggestions or inquiring about the situation. I definitely believe the mental health issues are a factor in the estrangement but not sure if she is consciously choosing this, maybe one of her other personalities is in control and doesn't know of her father? The mother is a very manipulative person and who knows if she has suggested things to turn his daughter against him? He has very little information to go on but does know she was involved in drugs due to a criminal record he found, he does not know her whereabouts but has found a few various Facebook accounts affiliated with her. The mother knew some information earlier in the estrangement but not sure if the daughter has not had contact with her the mother as well. If mother has had contact, she is not sharing any info with him.
Looking to offer him coping mechanisms to deal with this loss. But being a parent myself, I can not even imagine my daughter just disappearing without knowing where, why, for what reason- so many unanswered questions that only the daughter can answer.