I don't have any information on Cole Younger and he was not related to George Cole but, I have the following information.
John Cole married Eliza Foster on Nov. 12, 1867 in Christian County, Illinois. (Illinois Statewide Index - online).
The 1880 Everyname Census shows the following: Mt. Auburn, Christian County, Illinois - Page 591C.
Eliza Cole-keeping house-f-widowed-IL-(IL/IL)
John F. Cole-at school-10-IL-(IL/IL)
Charles E. Cole-8-IL-(IL/IL)
GEORGE W. COLE-3-IL-(IL/IL)
J.B. COLE-6 months-IL-(IL/IL)
John was married before and had a son named William and two daughters, Josephine and Alice.
My grandmother was Sarah BlancheGideon-born Feb. 14, 1881-Boliva, IL-(IL/IL). She's the one we heard was married to Cole Younger before George W. Cole.
Her parents were John Gideon and Alice Harrison. They were
married in Christian County, IL., June 5, 1880.
I hope this will help. Please let me know if you have any information I can use.