Actually, Audrey, it's not that big a coincidence.Jean Baptiste LaFontaine is not an uncommon name.(Jean Baptiste --John the Baptist -- is sort of a pun on LaFontaine -- The Fountain.)And there was a large immigration of French-Canadians into the NY/VT area during the Canadian depression in the late 1800's.Many came to the Glens Falls area to work in the paper mills.So many that they had started their own parish and school, to serve the French-speaking community.
St. Alphonsus Parish 4 Crandall St. Glens Falls, NY 12801
Your relatives are probably buried in the St. Alphonsus cemetery, on Luzerne Road in Queensbury, NY.I do recall that there is at least one Jean Baptiste LaFontaine in that cemetery who is not "ours".
Members of the French community often migrated in family-groups when relocating, and often intermarried.