Have you looked for their marriage or death certificates at the courthouse in Grand Haven? There's a good chance the parents would be listed. If you find the parents' names, I may be able to trace the family in the Netherlands for you. You would need to find William's grandparents' names also from his father's death certificate, since his father was born in MI. Once I know the names of a couple who were married in the Netherlands, I can very often trace the family.