I found a "Allen Turnbough" who married two Yeager sisters - Mildred Ann Yeager and Berilla Berry Yeager as his 1st and 3rd wives. Is this the Turnbough family you're looking for? If so the Turnbough family lived west of Hannibal MO (Marion Co). That's awful long way from Dunklin Co MO. Although possible, are you sure that it's Dunklin Co that is on the marriage license rather than another county or perhaps even a city? This Allen Turnbough also had a brother Samuel T who had a daughter Rose but no one in the family was named Harvey.