Call 0577 - 401150 (only available 8.30 to 12.30).
They will probably explain to you that you have to become a member of the NRPS studbook before they can list you as the horses' owner, and need to send them the passport so they can change the name of the owner in it.
The adress is
Postbus 3072
3850 CB Ermelo
Check with them on the phone first... There might be some differences to how it's done considering you're from england.