Molly Ziegler was the only daughter of Andrea Wyatt and Toby Ziegler. She had a twin brother, Huckleberry Ziegler. She was born at the end of Season 4 in "Commencement". Molly was named for the Secret Service Agent, Molly O'Connor, who gave her life trying to prevent Zoe's kidnapping at the end of season four. This appears to show both the extent of Toby Ziegler's bond with the Bartlets, and to 'absorb' Molly O'Connor into the family, conforming to the Jewish tradition of not naming for living members.