That is so recent that there's not much on-line. We need to know more: approx dob and dod for for William and Aggie, names of their children--besides John, anything. John's parents' marriage certificate would be the single most helpful document. I see some families in the census that are probably the right ones, but need some proof. Info from birth/marriage/death certificates would help us get the (correct) family back to the Netherlands. I would be happy to do that for you if you can get more information.
carlsonjm@hotmail.com