Claeys argues that the reason why De Kersemakere was known as Willem van der Haegen is that he must have been first married in Bruges to a lady named Van der Haegen (unknown first name, born around 1432, date of marriage unknown, date of death before 1469). The conclusion is that on the Azores, according to Portuguese tradition, Willem's children from this first marriage must have chosen the surname of their mother van der Haegen or da Silveira, but without their father's family name "Casmaca", as it is also the Portuguese custom.