Betty was created for Harry G. Petter and William Moulton Marston, in Sensation Comics #40. Created by the Wonder Woman creator.
Major Story Arcs
Betty was chosen by Wonder Woman because she looks just like her.
Wonder Woman had to go to a costume party where the international spy Countess Draska Nishki would be. Diana chose Betty to be disguised as Wonder Woman, while Diana went in a costume that was Betty's.
At the party Steve Trevor and Betty end up kidnapped, Diana manages to track them down and switches places with Betty again and ends up arresting Countess Draska.