Hello, My name is Anthony Isbill,Jr. and I have maybe a story for the name change, now this is just a family story told to me by my Grandmother, Rose Penoff Isbill ( married to my paternal Grandfather Howard Earl Isbill), so I don't know how much of it is true, but if it helps..I'm glad.
This is as much as I know ( which isn't much).
Around the Civil war time there were three brothers with the surname Esbill ( or something like that). But when they were soldiers in the Civil War, each one took on a different spellng of the last name, so that they could be recognized in case of death or capture or whatnot. To my knowledge they were split off into Esbill, Isbill and Isbell. Now it has been a while since I heard this story and I might be remembering it wrong. I cannot go back and ask my grandmother the specifics as she passed away two years ago. Anyway, just a little bit of info that might help you (I know it isnt much, but I can offer what little I have :-) )