Hello, A-dad!
I may be in your shoes one day, so I can't speak from experience yet, just from what I've thought we would do in a similar situation.
I think it might help answer questions for your daughter to meet or at least have direct contact with her birthparents. Even a one-time meeting sometimes satisfies her feeling of loss.
I would recommend posting to the Birthparent/adoptive parent board for communication between birth and adoptive parents. You'll not only get thoughts from other parents who have been in your shoes, but also from birthparents who have established contact with the child's adoptive families. It can be very helpful. Here's the link-
http://forums.adoption.com/forumdisplay.php?f=736