And I could see a Garth and Kaldur-like situation like LightningRider suggested with Donna and Cassie; that Donna might exist as a character in Earth-16 but just never became Wonder Girl. And there is plenty of time for Donna to have existed in Earth-16 since the Wonder Woman of the show is youthfully immortal considering the fact she was born 1925 and is 85+ years old (that info came from Ask Greg FYI).