The petitioner shall give not less than three days written notice of any proceeding at which a preplacement report will be considered to all agencies, any court approved individual, or any court employee requested by the petitioner to make a preplacement report. The notice shall state the name of the petitioner, the cause number of the proceeding, the time and place of the hearing, and the object of the hearing. Proof of service on the agency or court approved individual in form satisfactory to the court shall be furnished. The agency or court approved individual may appear at the hearing and give testimony concerning any matters relevant to the relinquishment or the adoption and its recommendation as to the fitness of petitioners as parents. The agency or court approved individual may in writing acknowledge notice and state to the court that the agency or court approved individual does not desire to participate in the hearing or the agency or court approved individual may in writing waive notice of any hearing.