Do you remember Uncle Bub before Uncle Charlie?
William Frawley, aka Fred Mertz.
How about Mike (Tim Considine ,I think) before Ernie. Just like Adam Cartwright in Bonanza, the oldest son left after the first couple of of seasons. I think Tim Considine was the soldier George C. Scott slapped in Patton.
".....and as Bub, William Frawley."
The storyline was that Bub and Charlie were brothers (their last name was "O'Casey.") William Frawley left the show due to poor health, and died shortly afterwards. Since nobody ever died on TV back then, it was explained that Bub decided to move to Ireland, with his brother, Uncle Charlie, moving in with the Douglas family as Bub's replacement.
Bub was they’re grandfather and yes I remember. I had a crush on little Ernie.