Good theory about Jean and Marie being John & Mary. What’s interesting about all these Compos is the religion. Even in 1861 at an advanced age John & Mary still were Roman Catholic (most all French Quebecers are RC) while all the boys were protestant. I can understand Antoine marrying an American, likely W. Methodist out of NY but what about Isaac and the others? If Antoine is the son of John and Mary, he must be the oldest, born 1807 to 1810 according to various census records. John’s wife Mary was born in 1791-92 making her someplace between 15 to 19 when she would have given birth to Antone. With Isaac born about 1825, Mary was still young but still quite a spread between Antoine and Isaac. My old uncle Jim Compo born 1890 told me the Compos originally came from France and changed their name from Compeau to Compo and also thought they originally settled in the US before coming to Canada but just a story. Where did you find the 1839 to 1848 Yonge Census records? Are they online?