I have the marriage license for William Letendre and Elizabeth Schaffer. They were married Sept. 4, 1917 in Montana. His parents on the cert. are listed as William Letendre & Miline Fayon(probably not spelt right).
My mother in law Mabel was the daughter of William John Letendre and Elizabeth Shaffer. Mabel passed away but there are brothers and sister still alive today. From thier family knowledge they list the children pretty well the same as you listed except for these differences.
1.Rosalie married Pete Tremoine(also called Ross) 2. Marie Angele married a Charles(surname) 6. Helene married George Neovard(they are buried at Battleford) 3. William John Letendre Born 1885 was the one married to Elizabeth Shaffer(the marriage cert I have a copy of)
I will sort this out with the surviving family. They have more birth cert. etc, but I do not have these copies yet.
Thanks so much I will keep digging for more.This is the right branch just needs some adjusting I'd say.