If you need a family contact in Holland, then please consider Willemien's oldest brother, Hein:

Physical address:

Curaҫaostraat 6,
2585 XZ The Hague,
Netherlands.

Tel no: +31 70 3507213

or her younger brother Ton:

Physical address:

Rietveld Schröderpad 33,
1064 WX, Amsterdam,
Netherlands.

Tel no: +31 20 6831563