It's quite possible you are correct and I am wrong. The information that I have that connects George Robert Sprinkle to David Frederick Sprinkle came from someone else's research.I will query them.They may have somehow connected George incorrectly to David's family.However, the information from David Frederick back is definitely correct (though if this isn't your line afterall, I'm sure you aren't interested).
In any event, I would surely think your grandmother would know who her inlaws were, so she's probably right.I do have a Dennis Sprinkle in my database with Indiana and Florida connections.This man is Dennis Sprinkle, b. 18 Feb 1877, Carroll Co., IN & died March 1942, Tampa, Hillsborough Co., FL.His wife was Iona Maude Pierce.However this Dennis's father was NOT John.Rather it was Wilson E. Sprinkle of Cass Co., IN.I know that is correct as it is from my own research.I do not know the names of this Dennis' children.
See if your mother is familiar with the name Wilson Sprinkle.
I would surely like to resolve this. . .and want to make sure everything is correct.That's why these genealogy forums are so great.Gives us all a chance to contact other people and verify information.