Artikel 28

If a Contracting State has two or more territorial units in which different systems of law apply in relation to the recognition and enforcement of maintenance decisions -
1. any reference to the law or procedure or authority of the State of origin shall be construed as referring to the law or procedure or authority of the territorial unit in which the decision was rendered;
2. any reference to the law or procedure or authority of the State addressed shall be construed as referring to the law or procedure or authority of the territorial unit in which recognition or enforcement is sought;
3. any reference made in the application of sub-paragraph 1 or 2 to the law or procedure of the State of origin or to the law or procedure of the State addressed shall be construed as including any relevant legal rules and principles of the Contracting State which apply to the territorial units comprising it;
4. any reference to the habitual residence of the maintenance creditor or the maintenance debtor in the State of origin shall be construed as referring to his habitual residence in the territorial unit in which the decision was rendered.
Any Contracting State may, at any time, declare that it will not apply any one or more of the foregoing rules to one or more of the provisions of this Convention.