Since I have both the surname DeMER/DeMERS and town/township/county Clarence, Cumberland, Russell County, Rockland occurring a lot in my family tree because a large part of my Mom's MORIN family lived there (My GPa was born in Rockland and his Dad was born in Clarence Creek) I decided to take a look to see what I could come up with.
Although I have DEMERS, I don't have any in the area you're interested in, but I did find DAMOUR, DAMOURS, and D'AMOURS-de-COURBERON.
I thought I should tell you because sometimes researchers can come up with info using the alternate spellings they come across.
I have Antoine DAMOUR, Nicolas DAMOUR, Helene DAMOURS, Magloire DAMOURS (who was married to my G-GAunt Helene MORIN in Russell County), Renée DAMOURS and Charles D'AMOURS-de-COURBERON (who is connected into our MORIN family through his marriage to Marie-Barbe HARBOUR but much further back) if you wish to compare.
Perhaps these might help ... Good Hunting!