James H. Guill, in his book 'A history of the Azores Islands, Vol. 5, p. 140', claims that Willem's wife, Margarida, was in fact an illegitimate daughter of Amadeus VIII, Duke of Savoy and that her husband was an illegitimate grandson of John the Fearless, likely through the latter's bastard son, John, Bishop of Cambrai, although, his allegations are heavily contested by Claeys, because Guill never cites any sources for this information, and never consulted the archives of Bruges, or other Flemish sources, always referring to Willem as 'Van der Haegen', and never 'Casmaca' or 'De Kersemakere'. Instead, Claeys argues that Margarida was probably born 'Marguerite Zabeau' from the petty nobility of Wallonia, observing that since before 1322 the surname Zabeau is found on the regions of Liège, Luxembourg (Belgium) and Ardennes (with variants such as Sabau, Sabia, Sabiau). Claeys also notes that even if Margarida was in fact a Savoy, she was probably the daughter of other members of this family who settled in Wallonia, as he claims to have found two coats of arms of lineages named Savoi or Savoye (Jehan de Savoye, 1444). Also in the same region, there are records of Aimé, Count of Savoy (record of 23 December 1304, cartularum of 1 September 1316) and Jacop van Savoye, Count of Romand and Saint-Pol (record of 8 April 1484).