Farrer [Honors and Knights' Fees, vol. 3, pp. 314, 316] quotes conflicting statements about Sibyl's parentage, from the chronicle of Sibton Abbey[citing Monasticon, vol. 3, p. 636b; vol. 5, p. 559b] and Dugdale's notes of the chartulary of Coxford [citing Bodleian Library, Dugdale MS 39, ff.103, 103d]. Both these accounts make Sibyl the sister of John de Chesney and the daughter of a Ralph de Chesney, but the former identifies thisRalph with one who "came at the conquest", whereas the latter gives two Ralphs, father and son. In Farrer's chart pedigree (p. 314) he shows Sibylas the granddaughter of the Domesday tenant Ralph. As there seems to be no doubt that there were two Ralphs, and that John de Chesney was the son ofthe younger one, this seems to be correct.