Desperatemom, the Attachment Disorder Network (
www.radzebra.org) has a booklet for sale--basically at our printing costs--that is designed to help extended family members "get it". It isn't perfect, but it was written by another mom of an attachment-challenged child, so it won't be coming out of YOUR mouth. I think they are like five bucks or something. You can find more info on the website.
Also, I don't know your location, but ADN is having a conference in June in Atlanta. That would be a great opportunity for your extended family to come and learn something and for YOU to be surrounded by folks living the same life! I thought of the conference because I do a workshop entitled "The Good Mom" and that is exactly how you put it in your post. Boy, can I relate. The opening slide shows June Cleaver on one side and Atilla the Hun on the other!!!
Hang in there, we are all right there with you!