Susan Whitney Lyman (b. 29 May 1821 at Northampton MA, d. 1867 at Philadelphia PA) was my gr-gr-grandmother. Her parents were Theodore Lyman (b. 3 November 1784, d. 1833) and Susan[na] Willard Whitney (b. 1788, Northampton MA). They were married at Northampton on 2 or 9 [depending on the source] October 1806. There was another Susanna Willard Whitney--perhaps an aunt or grandmother or an older sister--who died in 1786. These facts are all new to me within the last month.
Your information about the Montreal connection is fascinating because it suggests a plausible account of how the younger Susan met my gr-gr-grandfather, Alexander Frederick Sabine (they were married at Montreal on 17 May 1842). His family came to Ontario from England about 1834, when he was 15. I suspect he eventually went to Montreal looking for work, and found it in the leather business of her relatives. Perhaps she was also working for them, or living with them, or just visiting.
I will be in Boston the 2nd week of June, and hope to get over to Northampton to look at local records on the Lymans and Whitneys. If you have specific information requests, perhaps I can find some answers while I am there. Use my e-mail address if you want faster response.