I would have Diana and Donna be the daughters of Hippolyta and Zeus. The name Wonder Woman is a title given to Themyscira's greatest warrior Diana and this will cause a little rivalry between the sisters. The Wonder Woman costume would look like something worn into battle by Greek warriors (kinda like the WW style costume worn by Lois on the Smallville show) and would be red and black. After the return of the Greek Gods (see how I would do it Justice League) Dianna would become an ambassador to the U.S. and would change the colors of the costume to red and blue. When Diana prepares to leave home Donna volunteers to go with her. Donna would fall in love with America and want to become a hero herself. Donna's costume would be black with red stars (like the one she wore in Titans only not as low cut and I would trade the silver boots with the black and white ones worn by Wonder Woman in the new 52. While in America Wonder Woman would discover that Zeus had come to earth fifteen year prior to the Greek God invasion and fathered another daughter Cassie Sandsmark. Wonder Woman would train Cassie and she would take the name Wonder Girl.