Engeltron Of de Paris - Sources

Does someone have the source that Validates this profile's existence as the daughter of Bégon, comte de Paris, marquis de Septimanie and Alpaid DE AQUITAINE

With 3 other children born before 1816 (Bego's death) when their mother was only about 23 or 24
(Susanna, Leuthard, bur. 3 January, bef. 869, count & Eberhard, d. bef. 8 June 871) as it's getting a bit hard on the poor mother to be adding more children.