Grandma, what a lovely, touching story. Adoption and open adoption work for some. What an amazing gifts; of life and from the heart.
I work as a labor and delivery nurse. I see many different situations. Some similar to yours, and others that accept what God has given them, even though, from unorthodox situations.
I'm not an overly religious person, but believe that everything happens for a reason. Your daughter made a very grown up decision at such an early age. She is blessed to have the heart, strength, and courage she showed. If you desire, please tell her what an amazing woman she is/was.