Confession,
Your father must have faced some mental anguish going through a Pioneer Service School, knowing his son has "left Jehovah." If he's just going to the school at 76, that means that he's pioneered for a year and had not attended previously. Your situation could have caused him to examine his belief system more closely but instead he chose to "get closer to Jehovah" just over a year ago. I suspect he thinks of you at nearly every door he knocks on. He has good news to share with others, knowing his own son won't get "life." It's a hollow, empty feeling.
Sixteen years ago this month our son was df'd. My wife and I had not yet experienced our epiphany and were still true believers, although disheartened. We tried to continue pioneering but each step in field service was painful and heavy. In an ironic twist, the circuit overseer called. He was leaving his assignment a week early after three years. Could I fill in for him as pioneer school instructor? I agreed. It was a very melancholy week for me, performing almost on autopilot. It felt hypocritical at best, nearly traitorous.
Your dad must be feeling some of this. It's torture. The "visitation" you've so successfully navigated with the skillful assistance of your wife, is a superlative rescue attempt on several levels. It may or may not spark real introspection by your parents, but it has to give you some peace of mind.
tms