Thanks so much for your reply, sometimes it takes a fresh pair of eyes to spot things.
The Gatineau Valley Historical Society just emailed me with the wedding entry of Richard's son Thomas McAndrew and Ellen Flynn. Her parents are Patrick Flynn and Honora Rice of Co. Mayo Ireland, so she is the sister of my gg-grandfather Dennis Flynn who livedLow, Quebec.
I've also found a 1846 passenger list to Canada on ancestry.com which has a Richard McAndrew listed, just below him is a Dominick Barret, and squeezed between them is a Mary ?
So I'm wondering if I'll find out that Mary Barrett McAndrew of Templeton , Quebec ( b @ 1795 Ireland) is related to the other Barrets in Templeton: Patrick ( Sarah Burke, Ann Flynn ), Peter , Dominick ( Sophie Flynn), Bridget ( Charles Flynn), and Cecelia ( Corrigan ?), these Barrets being from Co. Mayo Ireland.