Please hold it just a minute here. John Mayhew Bill was my gr. gr. gr. grandfather and I have his marriage date to Sarah DeWolfe as 16 July 1811, NOT 10 June 1808 when he would have been only 16 years old! Can you tell me where you found that date? And where do you come up with Gurdon "D>" Bill being born in 1812? I think you mean just plain Gurdon Bill.
John Givan Bill was born 23 July 1863 in Billtown, the third child of John Leander Bill and his first wife, Margaret Ann Rankin. Their next child was Gurdon DeWolfe Bill who was born in 1863. If you both need more help with these line I will provide it as time allows and will forward your queries to a distant cousin, Gail Munro Clifford, in Mass. for her perusal. You might also see if you can find a copy of both Ledyard Bill's 1867 History of the Bill Family and Harry F. Bill's more recent book on his own line. Harry is the last Bill living in Billtown and gets his mail through Centreville.
This line of Bills is a long and complicated line eminating from three who were New England Planters who went to Nova Scotia from Connecticut in the 1760's. It requires a great deal of care not to make mistakes with it. Good luck!