I sure hope you have since found some more info. I am probably a cousin of yours, daughter of Bob Roesbery. I feel like I am beating my head against a wall when I try to research back into France for either Frank or Claude who was JB's father-in-law and also a Guillemin.
I did learn that Guillemins went to Canada, New Orleans, Australia and the US. I wishFrance made it easier to trace family trees. My research there is so hampered by my lack of the French language.
I am on Ancestry and my family tree is Jeanette Roesbery Family tree.
I suspect you may be related to my dad's sister Geneva?
Anyway nice reading your post, hope to hear from you.