About Sibyl verch Rhys Jones
Mistress of Sir John Perrot, and mother of Sir Perrot and of a daughter who married David Morgan. See Notes on the Perrot Family in Archaeologia Cambrensis, Third Series, XLII, 101-132 (April 1865).
An older version of this Geni profile claimed her as a daughter of Sir Thomas Jones, presumably by his first wife Elizabeth Done (otherwise, if daughter of his first wife Mary Berkeley, she would have been a half-sister of her lover Sir John Perrot).
However, the website Perrott's of England & Wales calls her Sybil ferch Rhys Jones -- Sybil, daughter of Rhys Jones (visited Mar. 16, 2014).