Synonymous with Wonder Woman is the Holliday Girls, a sorority that operated out of Holliday College became the Amazing Amazons' unofficial sidekicks. Both were headed by their unofficial leaders, Etta Candy, on each world. In the modern era of Earth-One, these primarily consisted only of a select few gals that joined Etta on their hero's adventures for a short period of time. These three were Tina Toy, Thelma Tall and Lita Little. This quartet would aid the alter ego of Princess Diana in a half dozen cases, then return to lives of normalcy except for Etta who would graduate and join Diana Prince in her clerical job at the Pentagon. On one occasion, Candy would duplicate the process that turned the evil Doctor Psycho into the super powered Captain Wonder by transforming herself into a red-haired Wonder Woman for a brief time in order to defeat the Doctor/Captain and other costumed crooks who had assembled on that occasion.
As for the Holliday Girls of Earth-Two, they had a much larger membership and several more adventures with their Wonder Woman over the years. Etta's primary pals in the group were Eve Brown, Roberta "Bobbie" Strong and Glamora Treat. On one such occasion, these three along with a few others were investigating the sinister Anton Unreal, who had devised an instrument that could project individuals into the fourth dimension. And it was in this reality that two significant things happened. First, that five of the Holliday Girls were transformed into replicas of Wonder Woman and, second, that they began to learn how to phase between dimensions. This latter skill would be used on future cases, including once when they were summoned to the planet Venus and later still to determine the true culprit behind a rash of crimes.
Again, note the extra members of the Holliday Girls on Earth-Two, during their scores of cases with the Power Princess. Three of these heroines would be the counterparts of Earth-One's Wonder Girl aka Donna Troy as well as earlier manifestations of Princess Diana herself as the first Wonder Girl and Wonder Tot. Wonder Girl was found by Wonder Woman as an orphan in a tenement blaze and raised on Paradise Island until her teenage years, having been granted with the same set of superhuman powers as her older step-sister Diana. Assuming the alias of Donna Troy, with no past, she carved a future alongside the Teen Titans before ultimately getting married to college professor Terry Long. On Earth-Two, Wonder Woman wasn't around yet so when that world's Troy was in a similar fire, firefighters saved her. Taking her to an orphanage in the late 1930's, she soon ascended into the ranks of a member of the Holliday College where this Donna Troy became acquainted with Etta and her pals. And thus, she too became a "Wonder Girl" if only briefly, sharing dozens of adventures alongside the Amazonian Princess. As for the original Wonder Girl and Wonder Tot of Earth-One, virtual duplicates of themselves were created by Queen Hippolyta for a series of Impossible Adventures, as had been the case when Earth-Two's Wonder Woman brought some of the Holliday Girls into the Fourth Dimension to combat Anton Unreal and on future tales making them her replicas. The fifth gal on this caper Virginia True would correspond to Wonder Girl's adversary Perfection aka Miss Maple, who tried to steal Amazonian secrets of life and was defeated.