Make sure your Granddad doesn't give his logbook away or make any alterations to the entries in it - 50 Penalty Unit Strict Liability offence times two:
No worries there, the last entry was well over 7 years ago.
I would have loved to have been at the point I could have had his name in my logbook as co-pilot, but unfortunately my flying has not been able to progress as I would have wished. Reading his stuff has motivated me, but motivation doesn't print money. I take heart that his flying noticeably was on hold for kids, so all is not lost, but just not well timed.
Share all your thoughts with your grandfather and ask all you questions now. Everything that you can think of.
We had some chats a few years ago when he was in a better state, but I always kick myself later for not being able to think of enough to discuss. I also hate the thought that I might feel like I am doing a final inquisition.