Cool info you have!Better than the average library.
None of the names you have ring any bells.My Tessier/Tacey clan arrived in the late 1850s to avoid clashes over their involvement in the Underground Railroad and the theft of a horse near Sarnia.They hid out on an island in the Saginaw until they were sure they wouldn't get in trouble.
I must admit, I'm not familiar with Jean and Pelagie.Do you know which of Urbain and Marie's children he descends from?
Re. your efforts to date their arrivals, there was a history of St. Clair published ca. 1885.The Burton in Detroit should definitely have a copy of the book, though in Special Reserve and not general circulation.Most of the early families are noted there in one way or another.Don't know if it'll help, but it is a very rich resource for the first 50 years of the county's history.
It is interesting how many Tessier/Lavigne descendants were scattered across the countryside.If you ever get a chance to scan in the docs and post them, I'll bet an aweful lot of people on this site would love to peek at them!