My dad lived to be 89-plus-months, and in his last 25 years or more started adopting various neighborhood kids as his surrogate grandkids. When he died, licensed to drive without glasses I like to recall, his mourners filled the rather large church sanctuary, and side chapels, many and various cohorts of his colleagues, friends, swimming buddies, etc. etc. And a number of his grandkids, who had consulted him through childhood and teenage, through courtships, marriages, divorces, career turmoil, births, family deaths, gardening and cooking dilemmas, and other aspects of life. Though his career was not teaching, he was a natural-born professor, loved to answer questions and give thoughtful and sometimes uncannily insightful advice. Brad, you are a natural-born dad and grandpa, and these girls would be fortunate and greatly helped by having you as a grandpa. Eventually, I would give them each a framed copy of that photo of you decked out in your suit (they will know that was special dress for an occasion), so they can always have it to jog their memories. Go for it, absolutely. No question. It's as much as done.