Media boss Lachlan Murdoch is seeking to sue more senior figures of news outlet Crikey's publisher, claiming they played a "highly-active role" in defaming him.
The Fox Corporation chief executive launched proceedings over a June analysis piece about the January 6, 2021 insurrection by Donald Trump supporters.
He claims to have been caused serious harm by the Bernard Keane article after it referred to Fox News and the Murdochs as "unindicted co-conspirators" in the deadly event.
The eldest son of Rupert Murdoch in August sued Crikey's publisher, Private Media, its editor-in-chief Peter Fray and political editor Keane.
Private Media denies the article was defamatory and is arguing a new public interest defence.
The Federal Court on Thursday heard Mr Murdoch has now sent concerns notices to Private Media's chairman and co-founder, Eric Beecher, and chief executive, Will Hayward.
Sue Chrysanthou SC told the court the action against Mr Beecher and Mr Hayward centred on the republication of the allegedly offending article on August 15.
The story was removed from Crikey's website after it received a legal letter from Mr Murdoch, before being reinstated weeks later, the court has heard.
"We've come across information that demonstrates a highly-active role, which we would say makes them publishers within the principles set out in the High Court, principally Voller," Ms Chrysanthou said.
She was referring to a High Court judgement on defamation proceedings brought by former Don Dale Youth detention Centre inmate Dylan Voller, which affirmed publishers are liable for third party comments.
Ms Chrysanthou said it would be alleged Mr Beecher and Mr Hayward "planned and pursued" the republication of the article.
Mr Murdoch is claiming the decision to repost the story is an aggravating factor in his case.
Clarissa Amato, the barrister for Private Media, says it will oppose an application to join Mr Beecher and Mr Hayward to the current case.
She said doing so would "bomb the hearing date" set for a nine-day trial in March 2023.
Ms Amato also said the application had been made late in the proceedings, and appeared to "recast the nature of the reposted article".
Justice Michael Wigney will hear an application to join the new respondents on January 30.
