It seems quite possible that your Janet Gillies (b. 1827) of Ardnamurach witnessed the marriage of my Janet Gillies (b. 1816) of Earnisaig/Stoule to Archibald McKinnon in 1848. Perhaps the two Janets were cousins. I have not researched any other Gillies/MacGillis' in Glengarry County. I am not actually related to Janet, but to her husband Archibald and his first wife, Ann. I had not heard of Captain Donald of Stoule. What documentation is there about him? Sorry I can't be of more help.