I have been working for many years to try to find out the origin of Ducharme of Louisiana. I don't have the final answer, but I found some clues.
Before going any further: I remember exchangin a few emails around year 2000 with a person named Betty Cormier-Ducharme that was living in Louisiana, but I lost her email address since. Are you that person? If so, I will read again what we wrote at that time and I will try to start from that point. Maybe Denise Pelletier is also able to help.