The only source I can find that says that Thomas Curtis' widow married Robert Bristow is John Bennett Boddie, in "Historical Southern Families", Vol. 12. Every other source names her as a daughter of Thomas Curtis. As Thomas Curtis was born c. 1600, it is much more likely that Robert Bristow (b. 1634) married his daughter and not his widow. See also Virginia Magazine of History and Biography, Vol. 14, p. 92, citing a Curtis family manuscript that names the Averilla who married Bristow as daughter and not widow: https://www.jstor.org/stable/4242784?seq=4