Once you're logged into geneanet
https://gw.geneanet.org/garybrunette?n=de+mornay+du+plessis&oc=...
Also
https://en.geneanet.org/profil/sergius42
also
Biography ==
=== Birth ===::Date: 1694
:Place: Ireland
=== Parents ===:: The Stamouers entry lists Judith *Ireland 1694 [tydens die terugrit na die Kaap], as the daugther of Jean Prieur and Marie Buissett. '''But this must be an error''' because Jean married Marie in Amsterdam in 1700, after which they returned to the Cape. According to French Speakers at the Cape (M Boucher), in discussing Jean Prieuer's return to Europe From the Cape (p 345): "''The movements of the family after reaching the United Provinces are uncertain, but it is known that a daughter, Judith was born in Ireland - or possibly England - in 1694. Du Plessis may have joined the Irish settlement scheme for French Refugeees undertaken at this period, or perhaps had English family connections. The surname is not infrequent there: Francois du Plessis was the first chaplain to the Protestant Hospital in London which opened in 1718;Philippe du Plessis, like Jean Prieur a surgeon, lived in the Tower of Liberty of the English capital in 1702.''" <ref name=WENDY>May 15, 2014 by [[Trollip-5 | Wendy Schoeman]]. Source: Dormay du Toit's research.</ref>
: "''Menanteaus, perhaps relatives of Jean Prieuer's wife, were still living in Amsterdam in 1699, while at Delft in May 6, 1691, the child Louis, son of Charles Marette and Judith du Plessis, was baptized. Charles, with his brother Louis, had come from Loans, near Deux, with Gideon Malherbe in 1687, abjuring Calvinism in order to escape. Could his wife have given the name to Jean Prieuer's daughter? This family connection is merely conjectural, but what is certain is that Jean Prieuer du Plessis was in Amsterdam by 1700 and that his wife had died by that date. His subsequent marriage to Marie Buisset in the Nieuwe Kerk of Amsterdam suggests that his wife's family had been long resident in the United Provinces.''" <ref name=WENDY/>
"'It seems, therefore, that Judith du Plessis was the daughter of Jean Prieur du PLessis and Madeleine Menanteau.'''"
https://en.geneanet.org/profil/sonjahoile