My granddaughter has lived with us since she was born 12 years ago. Her mother, has asked that we adopt her. How hard will this be to do? My daughter has sole legal custody of our grand daughter and the father has not seen her for four years.

You will need to try and get the bio father to relinquish his rights as well as the mother. Without that, you may not be granted formal adoption. Is there a reason you need to formalize the adoption?