Sydney man Naveed Akram is accused of targeting a crowd of people celebrating Hanukkah at Bondi Beach alongside his father, 50-year-old Sajid Akram, on December 14.
The alleged terror attack left 15 people dead, including a 10-year-old girl, and dozens more injured.
The elder Akram was shot dead by police, while his son was taken into custody.
He has since been charged with 78 offences, including committing a terrorist act, 15 counts of murder and 43 counts of attempted murder.
Akram has not yet been required to enter pleas to any of the charges against him.
After the identities of those injured in the attack were protected by a suppression order in January, a judge on Wednesday extended gag order to cover some nominated eyewitnesses.
The order prohibits the publication of any information that would tend to identify a group of 20 people.
On Wednesday, Downing Centre Local Court Judge Karen Stafford said she made the order to protect witnesses and victims from re-traumatisation and threats to their safety.
"The psychological trauma of bearing witness to a mass shooting is real," she said.
"In addition to threats, there is real risk to the physical safety of witnesses and their families. This risk is not hypothetical."
Judge Stafford said the order was intended to ensure that other witnesses would not be deterred from giving testimony out of fear that they might become targets.
She noted threats continued to be made towards Jewish people in the aftermath of the shooting, including towards witnesses at the royal commission into anti-Semitism.
Those who have chosen or later choose to go public on their own terms can do so.
The father-and-son attack was Australia's deadliest mass shooting since the Port Arthur massacre in 1996.
The men allegedly tossed three pipe bombs filled with steel ball bearings and a tennis ball bomb into the Hanukkah celebration at Archer Park before opening fire.
None of the bombs detonated.
A box-like bomb was also allegedly found in the car, along with two hand-painted Islamic State flags.
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