I think I have your proof.The following are listings in the Diocese of Baton Rouge Catholic church records. Please note that the name "Stampley" is not always spelled that way. 1.William John Stampley (William Stampley and Florestine Comeaux) m. 14 Feb. 1876 Marie Irma Langlois (Omer Langlois and Marie Josephine Dardenne) wit. W. J. Stampley, James Edmonston, Frank Stampley, C.R. Langlois (SJOBR-19,173)
The James Edmonson listed is my father's grandfather.
2. Marie Cleona Stamplon (John Wm. Stamplon and Marie Irma Langlois) bn. 3 Dec. 1876. Spo. Josiah Brown and Emille Commeaux.
3. John Reginald Stapley (John Stapley and Marie Emma Langlois) bn. 16 Feb. 1880 spo. John Terrel and Laura Brown
Because her name is listed as "Irma" on the birth,I would think that this is the correct spelling.
My 1st Stampley ancestor is Elizabeth Stampley.She is the sister to your John William's father John William Stampley m. Catherine Florestine Comeau.This means we are definitely cousins.Can send you more on all the ancestors.May be better to use email.What do you think?