Willem Cuser bastard son of Jan II van Avesnes (d. 1355) Parents John I of Hainaut Children Coenraad Cuser Siblings Alice of Hainault John of Beaumont Jan van Oostervant Aleida de Hainaut Isabelle of Avesnes Simon Heer van Bruelis Marguerite d'Avesnes William I, Count of Hainaut Mary of Avesnes Partners Ida van Oosterwijk