For better or worse, I've decided that the Robert FAIRBAIRN who emigrated to Ontario who supposedly had children: Elizabeth, Alison, Jane, William, James and Robert, is another son of Archibald FAIRBAIRN and Alison CROSSER.
This is admittedly conjecture, but based on several bits of circumstantial evidence, a lot of which hinges upon Napanee as a place in common.
Would love to hear from anyone who can comment authoritatively either way, especially as I've also decided that the William who married Catherine MORGAN is his son William.
Webpages updated to include identified family to date in the descendants charts, and to give Robert a page of his own to outline some of my reasons.
Related surnames: FITCHETT, GRIEVE, STRAIN, MORGAN, HAYNES, and in the next generations: VADER (no not Darth), FRENCH, GOULD, ROBINSON, VINE, GARRISON, ANDERSON, HEFFERAN, FRISKIN, GILLESPIE, SMITH, PAGE