I think you found the key to the problem!Thank you so much! I was usomg the name from Inez's death cert which lists family name and father as Hemmle, birthplace as Defiance, OH. The info you found fits family history, since the Duck family lived in Dekalb Co/Auburn, Garrett for a number of years until some of the children, siblings of Luther, moved to Texas sometime after death of their father, some of them prior to 1900.
I am not sure that her family moved down there; I suspect Luther married in IL, possibly Chicago, but maybe elsewhere, since he had a sister who lived elsewhere in IL for awhile prior to going to Texas.His stepmother, her child by his father, and that sister apparently went to Chicago subsequent to father's death.
Appreciate that info so I can take that family line back further!