The wife of Van-Zee and the mother of their young twins: a son, Lyle, and a daughter, Lili. Sylvia is â€œan exact doubleâ€ of Lois Lane. Born Sylvia DeWitt, a â€œrich young heiressâ€ from â€œa bustling mid western city,â€ Sylvia first meets Van-Zee, a citizen of Kandor, during a period when Van-Zee is living in the world outside Kandor after having been accidentally enlarged to full human size by Superman by means of the ingenious enlarging ray developed by the renegade Kandorian scientist Zak-Kul. After the couple have courted, married, and settled for a time on the planet Venus, and Sylvia has given birth to their two children, Superman reduces the entire family to microscopic size with Brainiac's shrinking ray so that they can all live happily together in Van-Zeeâ€™s native Kandor (SGLL No. 15, Feb 1960: â€œThe Super Family of Steel!â€ pts. I-IIIâ€”â€Super-Husband and Wife!; â€œThe Bride Gets Super-Powers!â€; â€œSecret of the Super-Family!â€).
It is in Kandor that the family now resides. Superman visits briefly with Van-Zee and Sylvia during an adventure in Kandor in January 1963 (S No. 158: â€œSuperman in Kandorâ€).