In 1850, Millie was already married to Abner Porter. They were living in the midst of the other Fox families. Abner was 27, Milly 23, William & Benjamin were both 3, presumably twins, Alexander age 2, and Elizabeth age 1. They lived next door to William Porter, age 60 & b. in NC, whose wife was Ruth age 52, and seven young adults and children. William is likely Abner's father. The surname was spelled "Poter" in this census, and indexed as "Pater".
By 1860, Abner & Millie's family had changed. Benjamin age 13 was there, and Elizabeth age 11 - apparently William & Alexander had died. Amanda was age 7. William Fox age 22 was living with them doing day labor - probably a cousin of Millie's.