I have a Duncan McRae born Rosshire Scotland who died ca 1835 in Glengarry ON. He married Janet McRae bn ca 1797 Scotland, died Ontario 1882. (This was Janet's first husband-2nd husband also a Duncan McRae.) Their son John McRae (born ca 1828 in Cape Breton NS) married a Catherine McGillis (born ca 1838 in Canada).
Are these possibly of the same McGillis and McRae families you are researching? They were in Glengarry from about 1835 to about 1850.