(b) The petition for review shall be filed in the appellate court and shall specify the parties seeking review and shall designate the respondent and the order or part thereof to be reviewed. The administrative agency and all persons, other than the petitioner, who were parties of record to the proceedings before the administrative agency shall be made respondents. The method of service of the decision shall be as provided in the Act governing the procedure before the administrative agency, but if no method is provided, a decision shall be deemed to have been served either when a copy of the decision is personally delivered or when a copy of the decision is deposited in the United States mail, in a sealed envelope or package, with postage prepaid, addressed to the party affected by the decision at his or her last known residence or place of business. The form of the summons and the issuance of alias summons shall be according to rules of the Supreme Court. If, during the course of a review action, the court determines that an agency or a party of record to the administrative proceedings was not made a defendant as required by the preceding paragraph, then the court shall grant the plaintiff 35 days from the date of the determination in which to name and serve the unnamed agency or party as a defendant. The court shall permit the newly served defendant to participate in the proceedings to the extent the interests of justice may require.