When the requirements for application of both the Inter-American Convention and the Convention on the Recognition and Enforcement of Foreign Arbitral Awards of June 10, 1958, are met, determination as to which Convention applies shall, unless otherwise expressly agreed, be made as follows: (1) If a majority of the parties to the arbitration agreement are citizens of a State or States that have ratified or acceded to the Inter-American Convention and are member States of the Organization of American States, the Inter-American Convention shall apply. (2) In all other cases the Convention on the Recognition and Enforcement of Foreign Arbitral Awards of June 10, 1958, shall apply.