Marguerite

Count Baudouin VIII had [one probably illegitimate] child [by an unknown mistress]:

9. MARGUERITE (-after Mar 1237). The charter dated Mar 1236 quoted below indicates that Marguerite was the sister of Philippe de Hainaut Comte de Namur (see above). The obscurity of her husband (who is not even described in the sources identified below as a knight) and the high profile marriages of Comte Baudouin VIII’s other known children suggest that Marguerite was illegitimate. The chronology of her life (based, it is true, only on three data points) suggests that she may have been born towards the end of her father’s life. Perhaps she was left, while still a child, in the custody of Philippe Comte de Namur when their father died. A charter of “Simon van Harelbeke” dated 1234 records that he and his wife left on pilgrimage to Santiago de Compostela in Spain[546]. Maybe Simon died during the journey as the following document describes him as “late”. “Bauduin héritier de l’Empire Romain et Comte de Namur” declared that, “feu Philippe Comte de Namur son oncle seigneur d’Harlebeke” having granted “le Gavene [type of tax] de Harlebeke” to “Marguerite sa sœur et à feu Simon de Harlebeke son mari” and their heirs for ever, “Marie fille desdits Simon et Marguerite” had donated it to Marquette on entering the abbey and that he now confirmed the donation to prevent “Marguerite sa sœur comtesse de Vienne” from disturbing the abbey’s possession, by charter dated Mar 1236 (presumably O.S.)[547]. m (before 15 Oct 1212) SIMON van Harelbeke, son of --- ([1234/Mar 1237]). http://fmg.ac/Projects/MedLands/FLANDERS,%20HAINAUT.htm#BaudouinVHa...