My Robillard family came from Pontiac county also, although I haven't had much luck in tracing them...but when I saw your post I thought maybe they were connected.
Do you know if Jean Baptiste had any siblings?Who his parents were? etc?The time frame fits in with my great great great grandparents...and probably they are somehow connected if they were in Pontiac County.
Anyway...my great great great grandfather was Alexandre Robillard (Born approx. 1795...died 1899?) and he married Marie Louise Edouard on September 21, 1835.I think his parents were Jacques Robillard and Marguerite Georges but I have been unable to confirm this or find any other information.
If you do know anything else on your family I would love to have the info! :)