Sorry but my French is not good enough for writing.
I believe that I have some answers for you. In the Drouin Cowan is spelt as "Cahonne" The marriage of Francois to Julienne Thomas is registered in Beauharnois, 3 August 1869. Parents: J-Bte Tessier & Marie Cohonne. Henri, shown as Henry, married Ernestine Daigneault, 19 August 1877. I have nothing on Roger.