The department shall employ probation supervisors. The department may assign one supervisor to each judicial circuit in this state or, for purposes of assignment, may consolidate two or more judicial circuits and assign one supervisor thereto. In the event the department determines that more than one supervisor is needed for a particular circuit, an additional supervisor or additional supervisors may be assigned to the circuit. The department is authorized to direct any probation supervisor to assist any other probation supervisor wherever assigned. In the event that more than one supervisor is assigned to the same office or to the same division within a particular judicial circuit, the department shall designate one of the supervisors to be in charge.