Try the stepparent adoption blog, I have written several articles on talking with children about adoption.
http://stepparent.adoptionblogs.com/index.php?cat=1552
It is hard when a child refuses to bond with a parent, there is also a section on bonding in the stepparent adoption blog, that you may wish to check out, let me know after you read through the blog if you still have questions or concerns and I will be more than happy to address them!
Julie