D.W.
Now that she is asking, she is ready. Explain that mommy's and daddy's have to make decision they feel will protect the kids and you guys felt that the time wasn't right until now. I wouldn't say that the birth father doesn't want to be involved. I would say he wasn't ready to be the kind of father that she deserved. You don't know how to get in touch with him. Have converstation about appropriate limits with her paternal grandmother if you let her be a part of your daughters life, i.e. the grandmother can not discuss the bio dad. My dad lived 30 miles from me growing up, and rarely came to visit us. I wondered about him and I'm sure your daughter does too. And try not to be hurt if she tries to find him. With the internet, he could be a few clicks away.