To the best of my knowledge, non of the people on my branch of the Duhamel family came from st malo or lisieux.
My people came from Trois Rivieres.
Question: How far back in the Duhamel tree can you go?
Try the message board on Genealogy.com - on the right top section there will be a place for you the enter the surname you are searching. Good luck!
Also- there is a French Canadian-American Center in Manchester, New Hampshire, USA. They also have a wealth of information - try googling them.