Without limiting section 609, the procedural rules may provide for the following:
(a) how a provision of this Act that applies in relation to an applicant for a protected action ballot order is to apply in relation to joint applicants for such an order;
(b) the joinder, with the consent of each existing applicant, of one or more bargaining representatives to an application for a protected action ballot order;
(c) the withdrawal of one or more applicants from a joint application for a protected action ballot order.