Yes, this line originated in France at the Norman source point. A Bill Decoursey of Minneapolis, in the 70s, performed extensive research on this line and I have copies of his letters on the subject. If you've not seen them, please E-mail me and I'll send along what I have.
A master reference is given by him as follows:
"The seat of our Courcy ancestors in the late 16th century was in the area of Rouen, Lille, and Avesnes in the northern part of France (at that time, part of this was Belgium). Some of the genealogy of the Courcy family as well as the related families of DeCroy, Provoost, Montagne, deChesne, Verbrug (VanBrugh), Truex, Vigne, Cuddebak, etc., can be found in the 10 volume set by Pol Louis Potier deCourcy, Histoire Généalogique Et Chronologique De La Maison Royale De France (Paris 1726) - Minnesota Historical Society Catalogue ## CS586/ff.A6/1726.