Victoria Police has lost a bid to keep secret an operational review undertaken after James Gargasoulas killed six people and injured dozens of others in the Bourke Street massacre.
The force will also have to reveal details of its new car pursuit policy to a coronial inquest into the deaths.
Gargasoulas led police on a car chase before driving down the city's Bourke Street Mall, killing six people and injuring dozens more in January 2017.
Lawyers for the police wanted to suppress a critical incident review done in the immediate aftermath of the tragedy but Coroner Jacqui Hawkins on Friday ruled it could be made public.
Victoria Police also argued Gargasoulas had known the officers would back off from the pursuit and so details of the force's new policy about pursuing suspects should be kept secret in the interests of public safety.
But Ms Hawkins ruled against the application and also ordered the inquest be expanded to look at the actions of police up until Gargasoulas' arrest.
Lawyer for the victims' families Aine Magee QC earlier said failures in other responses to the emergency should also be examined after 10-year-old Tahlia Hakin's father was led to believe his daughter was still alive and he was prevented from going to her.
Ms Hawkins on Friday said she was not convinced this should be looked at in the inquest.
But she did not rule it out and ordered the families be given access to the criminal brief, including so they could make their case to further expand the scope of the inquiry.
"There is evidence (in the criminal brief) relevant to Mr Hakin's concerns that will hopefully provide Mr Hakin and his family some level of peace in this respect," the coroner said.
"In the evidence presently reviewed, there does not appear to have been any opportunity for Mr Hakin to have saved his daughter's life."
The inquest had been expected to run from November 18 until December 20 but is now to be extended into February.
It will examine the justice system's treatment of Gargasoulas, including his release from custody during an out-of-sessions bail hearing just days before the deadly rampage.
However it will not look at whether or not the bail justice's decision was correct.
Gargasoulas was jailed for at least 46 years in February for what was described by the sentencing judge as one of Australia's worst examples of mass murder.