A grant was made by the Infante to his aunt, D. Isabella of Portugal (Edward and Henry's sister), the Duchess of Burgundy, in the Low Countries.

[10] Consequently, in 1470, with his wife, Marguerite, and at his own expense, he offloaded two ships carrying his extended family, slaves and professionals of various services, to begin what was characterised as a "second-wave" of immigration to the island (the first having been pioneered by de Hurtere in the 1460s).

But, sensing a level of bad faith on the part of de Hurtere and a growing rivalry,[11] he abandoned his holdings on Faial, to settle in Quatro Ribeiras, on the island of Terceira.

He began to cultivate wheat and gather woad plants for export (specifically Isatis tinctoria which was also produced in the Picardy and Normandy Regions of France until that time).

But his return was brief; after seven years he left Quatro Ribeiras and settled in the area of Topo, São Jorge Island, effectively establishing the community with other Flemish citizens.

He married Marguerite (née Zabeau[1] or de Savoie[12]) probably in Bruges, Flanders, (at times referred to by Frutuoso as Margarida da Sabuya, others would refer to Margarida da Sabina, Zambuja, Sabuia or Margarethe Sabuio) and would father eight children which would all integrate into the communities of the Central Group of islands: The Flemish surname van der Haegen comes from the word Haag, which means hedge, and is translated into Portuguese as Silveira[citation needed].

[13] In 2006, in his article 'Les Flamads au Portugal au XV Siècle'[2] the French historian Jacques Paviot wrote about the existence of a civil sentence[14] in the archives of Bruges, written in medieval dialects of French and Dutch, which details the commercial relations of an individual named Willem De Kersemakere with various Portuguese merchants, including Lopo Mendes.

Claeys' also claims that, according to the Flemish and Portuguese customs, men never receive the surname of their wives, thus, the denomination "Willem van der Haegen" would be incorrect.

[citation needed] In addition to Paviot and Claeys, several authors[7][8][5][3][4][6][15] throughout the centuries have referred to Willem as Guilherme Casmaca or Cosmacra (a possible linguistical corruption of Kersemakere), with the earliest attestation, besides the will of his wife, being a description of his life and family by Gaspar Frutuoso written in the years 1586-1590,[9] in chapter 36 of the manuscript Saudades da Terra.

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,[12] 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'.