I was interested in the origins of the Hadler name and happened across your message. The reason is rather lengthy but when I was in high school I was smitten by a Hadler and for various reasons have resurrected an interest.
It should be easy to research the Hadler name. Much easier than Hughes I suspect. By the way, my grandmother Winter taught Sioux Indians at Ft. Berthold ND. Kept a loaded pistol in the drawer I understand.