eldest daughter
"Jehan de Saint-Sauflieu, écuyer, seigneur dudit lieu, lequel épousa Mette, fille aînée de Philippe, bâtard de Namur, seigneur du Puis ou Nuis, 1445." (Titres de mariage.)
from p. 171, ANCIENNES REMARQUES DE LA NOBLESSE BEAUVAISINE...
Revue nobiliaire, héraldique et biographique. Publiée sous la direction de M.L Sandret. Troisième série - Tome quatrième.
The above is the only citation I can find naming the father of Mette (Yvette), only otherwise referred to as "fille du batard de Namur à Tournay." She was probably named after her maternal grandmother, Mette (Mahaut) de Laminne. As a daughter of Philip de Namur (who married Marie de Dongelberg in 1422), there is no chronological problem, as she would then have been between 18 and 22 years old when she married Jean de Saint-Saulieu.
General Notes: