Indiana Code Title 4. State Offices and Administration § 4-21.5-5-8

Sec. 8. (a) A petitioner for judicial review shall serve a copy of the petition upon:

in the manner provided by the rules of procedure governing civil actions in the courts.  If the ultimate authority consists of more than one (1) individual, service on the ultimate authority must be made to the secretary or chairperson of the ultimate authority.

(b) The petitioner shall use means provided by the rules of procedure governing civil actions in the courts to give notice of the petition for review to all other parties in any proceedings that led to the agency action.