how to explain attachment disorder to unbelieving family??

I have learned it is very hard to get family to understand. I no longer have a relationship with 2 sisters due to the fact that our adopted 14 yr old with RAD. They don't understand what we go through in our home because when around daughter she is very sweet and charming. I have gave them a book to read which also states the symptoms of RAD and the ones that she has which i over half. But they still don't see it. At age 15 daughter had got so out of control and with sister believing stories we had adopted daughter removed from home for her safety and ours.(was experiencing the good parent/bad parent)she was also starting to hurt other child in home. She was placed in a group home and we had bi-weekly family therapy for a year that did not help. DSS was involved due to sibling calling and relaying stories that adoptive daughter called and told her. Sister never called (since we leave out of town since daughter was 14) us to verify what was happening because they believe she was sweet and innocent. So I guess what I am trying to say is that some family members just don't understand. We lived with my mother for 3 months before we moved out of town and the once GD that she thought was innocent she learned by us living with her what exactly we experienced on a daily basis. You really have to be around a RAD child daily to understand the problems we experience which outside the home and around others the RAD child is very sweet and innocent. We no longer have adoptive daughter she was very persistent on not wanting to be in family and wanted to be adoptive by another family(she really doesn't understand the meaning of adoption)so with the suggestion of 3 therapist decided to voluntary relinquish our parental rights. 3 months later she decided she didn't get new family and wanted us back and state would not allow it. 2 years have gone by now heard about 6 months ago she was placed in another county in a foster home I believe a therapeutic one and have learned she is not happy there either. Tried to talk with her through email 6 months ago and she wanted nothing to do with us and responded very nasty. Just a few days ago she sent us an email wanting to know how I am and the family. then went on to explain how great she is and also that she has some questions she would liked answered. I have not replied back to her and feel she is just seeing if we are still there for her. Not sure what to do. Heard she is unhappy where she is at which I believe is because they are very structured and also the therapy might be getting to involved in her life (which she do es not like and will shut down or try to run from) Believe they are not using a therapist educated about RAD. Because she plays so sweet and innocent around the people that don't show her deep down love like she experienced , that they are treating her for just mainly some behavioral problems. I think there should be meeting where such as GP, sibling and family members can attend to help them understand what parents with a RAD child experiences.