How to contact the Dutch Central Authority to file a return request
The Dutch Central Authority is the first organisation to talk to if you want to file a return request. They will do some research before deciding if they will accept your request. And then they will start their out of court procedure, which will not cost you anything.
They will contact the parent who took the child to the Netherlands and see if he or she is willing to cooperate or to cooperate with mediation.
If that does not have any positive result, you will have to decide wether or not you wish to start a court procedure. Unfortunatily, the Central Authority will not pay the costs of the procedure for you.
You can read more information about international child abduction: