Subsequent to the filing of a petition for decertification, the Board may direct an investigation of all questions concerning representation, including, if applicable, whether the showing of interest requirement, as set forth in the FPAA, has been met; whether one or more bargaining agents seek to represent some or all of the employees in the allegedly appropriate unit; and whether there is an agreement among the parties as to the appropriateness of the unit.
Okla. Admin. Code § 585:35-3-7