As mentioned previously, lots of male superheroes were being given sexy female sidekicks as replacement for their teenage / young boy sidekicks in 1948. Merry, Sylvester Pemberton’s newly adopted sister, becomes Gimmick Girl in Star Spangled Comics #81 (June 1948).
On the Timely (Marvel) side, the Human Torch ditches Toro for Sun Girl who even gets her own solo magazine. Little is explained about Sun Girl, though apparently she was the Human Torch’s secretary and had no superpowers.