Hi Mae, congratulations on finding your connection to the Gareau dit St.Onge family.So lucky, I am stalled at one generation, sorry you and the others could not connect up with me too. I have seen many many variations of the Gareau surname. Here in NY we have seen Garrow, Gorrow, Gard, Garo and Grow.
My own family adopted the Gorrow version. Of course these were all because the census takers most of the time could not understand the thick French accents they used and just wrote it phonetically.
Good luck in your future research, keep me in mind if you think you find some connection. Kristin