The first wife of John Hurst of Fairfax County, Virginia (he died 1789), was apparently Elizabeth Summers. The question is whether she died in 1781 (and thus mother of all the Hurst children). But some sources say she died much earlier, and that John's second wife Sibyl Moxley was mother of the younger children. Either way, John's will (1787) calls his wife Sibyl.
John's profile currently makes Elizabeth Summers mother of all his children, and claims she died in 1781. However, some sources have him marrying Sibyl Moxley much earlier and mother of some of his children (see weblink below). So which is correct? I could find no source showing a 1781 death date for Elizabeth Summers, or a marriage record for Sibyl Moxley (either after 1781, or much earlier).
http://www.colonial-settlers-md-va.us/getperson.php?personID=I020811&tree=tree1