George Bopi was allowed joinder in the case after his lawyer, Nicholas Tame, asked the court to be joined in the judicial review proceeding as the third defendant.
Justice Collin Makail, in granting the joinder, directed all parties to file and serve affidavits they intend to rely on in the trial by June 29.
The case will return to court on July 3 for further directions.
Secretary Morola was suspended last month over serious allegations levelled against her relating to the process of issuing work permits to foreigners.
Bopi, the Chief of Staff to the Prime Minister’s Office, was appointed to act in the position after a government team led by Department of Personnel Management Secretary, John Kali, was appointed to investigate the allegations against Morola.
Her suspension was stayed by the Waigani National Court pending the judicial review of the National Executive Council.
The court was of the view that Morola had an arguable case to be tried in court and sufficient interest.