My branch of the Grondin family descends from Joseph Grondin who moved to the Detroit river region sometime in the late 18th century. Joseph married Archange Renuad in 1801. They start in Sandwich, drift around the Canadian side a little and end up in Amherstburg ca 1820. They had a number of children, including a daughter named Victoire Grondin who married a man named John Shaw in St John the Baptist parish, Amherstburg. John Shaw's parents are not listed. I have went through the church registry (on microfilm from LDS) and tried to track down these Shaws, or Chats or Chars and will be very willing to share this data from you. I didn't think of looking for Lechat or Lechar though.
Now, there is a book by Denissen entitled "Genealogy of French Fanilies of the Detroit River Region" which lists a family of a John Shaw, living in Detroit in the late 18th century. I haven't found a connection between my Shaws and these Shaws. The John Shaw described by Denissen marries three times and has children listed by the second two wives. One of these children is named John Baptist. One of the flaws in Denissen's book is that he anglicizes all of the French names so I am very confident that this person was known as Jean Baptiste Shaw.