It's been a while since I lurked here so I missed this message until now. I don't know if my family is yours so here goes with my lot.
John McColl, weaver in Duachy not far from Kilmelford, born in the 1720s,had several children of whom I know three, one was Angus.
Angus McColl, cottar in Kilmelford, born in the 1750s had nine children, the oldest Duncan baptised in Duachy on 7 Sep 1783 and I do not know what became of him. Four of Angus' children went to Aldborough and then scattered. Duncan did not come, but with so much family in the area it is perfectly reasonable that his own offspring may have made the journey later. The youngest of the emigrants was my gtgtgrandfather John who begat four children, two of whom (Angus and John) were the McColl Brothers who were the founders of McColl Frontenac.
I would love to know how you know about Duncan, and what detail you have that might link into mine. I'll happily email you it all should you wish.