Hext, Emmett Dalton, Bob Dalton and Harry Tracy are all right. Frank is the first name of the second one.
A clue for you and Hamp for his last name.
October 6th 1866 in Seymour, Indiana, he and his brothers committed the first train robbery in American history.
Clue for the third one is "Butch Cassidy".
I hope this helps.
Lady GB