You can search via this sites:
http://www.online-begraafplaatsen.nl/Default.asp?lang=engand
http://www.graftombe.nl/Graves are rented for 10 years and when the family decides to stop paying rent after that period the grave will be reused. Sometimes spouses are in the same grave or are buried next to each other.
I hope you have a great time in our beautiful province Zeeland.
Regards, Rian