Artikel 23

A Contracting State which has two or more territorial units in which different systems of law apply in matters of maintenance obligations may, at the time of signature, ratification, acceptance, approval or accession, declare that this Convention shall extend to all its territorial units or only to one or more of them, and may modify its declaration by submitting another declaration at any time thereafter.
These declarations shall be notified to the Ministry of Foreign Affairs of the Netherlands, and shall state expressly the territorial unit to which the Convention applies.