Bonjour Judy, Interesting details. If I get you well, Lombard Ducharme did marry a grand-daughter of Antoine Ouimette and Archange Chavalier.
Now this grand-daughter was the daughter of the first marriage of Elizabeth to Michael Welch (1830) or of her second marriage to Lucius Darling (1835 ?). In either case, marriage of Lombard Ducharme likely took place around 1850 to 1870. That narrows the picture a bit.
Now I don't know Wilmette Illinois, but there is a place called Willamette in Oregon. There was an important colony of French-speaking persons there in tne XIX century. I will check on that side also.
I will let you know if I find something. Do the same please if you find other details.