Hi Erin,
Make sure you go to Helen's site at
http://yax.tripod.com/yaxfamilygenealogy/ it is wonderful.
You can also go to your local library and see if they have the book called "Genealogy of the French Families of the Detroit River Region 1701-1936 volumes I and II" it is a wonderful book and you will find a lot about the Yax's in that book. They may be able to Interlibrary loan the book but if they do not have it but you will have to ask.
I hope that helps
Kathy