Talk him into the shake, I know all about being set into your ways but when I dry fly fished a lot I was a dry shake junkie. it works best when you tap a bit into the hand and crush the fly into it then shake to finish. I used to do that and follow with some Frog's Fanny to put them high & dry. They almost always bring up a fish after a good going over
So wonderful to have your dad for so long and I wish you many, many more seasons together.