Theriot Family Genealogy Forum
After posting the other message (re: the Y-cyr.ged file), I began updating the latest electronic postings at our Wisconsin Theriault's Home Page and came across this web site:
which discusses exactly what you are looking for. (That's pretty much the story of my genealogical efforts over the past 30 years. Information seems to just fall into my lap.)
Did you know about that site? Are you searching on all the 50+ spellings of the name?