I just looked on familysearch.com to see what information they had on Elisabeth Boisvert. It shows she was the only Elisabeth Boisvert born in Quebec in 1845. She was married to Samuel Young who was born in 1837 and of Scottish descent. Elisabeth was Catholic and Samuel was Eglisi d' angliterre which I think is protestant. All of their childern were Catholic although because their father was Scotish they were concidered of Scotish descent even though their mother was French. I guess that's the way it was in those days. You took the nationality of your father and his last name.
I am sure many of Elisabeth's relatives may have used the name Greenwood. Even though they were French, most Boisverts (Bawvair) prefered the name Greenwood when arriving in the United States It made life easier and some of them could pretend they were English and not be discriminated against. There were no questions asked when your name was Greenwood. You never have to spell it or pronouce it. Life was much easier for the person with the anglo name.