Anne, the information about the dates of death registrations in Ontario is new to me and will be useful in future research. Thanks for sharing your knowledge.
You're correct, John Bane was a MacLeor (or variant thereof) at birth in Glenelg in 1760, and when he settled at C7L29 in 1794 but other documents suggest that the family had adopted the anglicized Dewar by the 1820s (if not before). Certainly after his death in 1844, by the time of the first census in 1852 his widow and the rest of his family were enumerated as Dewars.
His sons were: William, John, Roderick, Angus and Donald John (b. 1804)
As far as I can tell there were never any Jameses in the family. Do you have a couple of stray Dewars looking for families?