Thank you for getting back to me, James.
Alexander Ban Kennedy looks like a good possibility. I note there are two Duncans in the list of his chidren. I'll need to check further, but I could imagine that the one born in 1807 might have died, and the later son (b. 1810) was given the same name. Mary Kennedy was born in 1845, which would make Duncan ca. 35. That would fit.
Interesting to have the name of Alexander Ban's wife as well, along with the (possible) names of his parents.
Thank you for helping me to find another piece of the puzzle. I have something concrete now to work with.