Thanks Janet for your suggestion to look at the "other" Kirkhill church (now United) for the burial of John Bane Dewar and the birth records of his descendants. It's always a good idea to cast one's net widely in this genealogy hobby. I've had a closer look at the history of the two churches.
John Bane and his family were in the first wave of Highlanders arriving at Lochiel (Glenelg Kirkhill) in the mid 1790s and would have been already well settled when the first wooden Kirk of Scotland was built in 1819. He died in 1844 before the congregation split in 1846-47 and the other (west) Free Church was established and the stone building dedicated in 1850. The plaque erected in 1874 at St. Columba Presbyterian (east church) commemorating the "founders" lists John B. Dewar's name. And the first census (1852) after John Bane death lists his widow Catherine and descendants as being "Church of Scotland" not "Free Church" so I don't think they were part of the breakaway congregation. I will go back and check later censuses to see if the family remained staunch in their affiliation.
Thanks again for your suggestion,