Your father does not count. And truthfully I don't think you will have a hard time conveying this message.

I simply wished to impart to her about how proud we are of Vergil. His road has not been an easy one, yet he has managed to find the courage to open his heart. For all deeds large and small that have touched us deeply. He has come a long way and still seeks to go further. And also to impart how much we love him. All sides of him, both human and demon. I imagine that would be quite comforting to a parent raising such children. Finally, perhaps most importantly of all, that we will take care of him to the best of our ability.