More than 10 years after he disappeared from his foster grandmother's home - and more than five after the inquest started - a coroner has ordered all submissions to be handed up by June 13.
The inquest into William's disappearance has examined search efforts for the three-year-old as well as the possible involvement of the foster mother in disposing of his body.
The toddler - who was last seen wearing a Spider-Man costume - went missing while playing on the verandah at his foster grandmother's home in Kendall, on the NSW mid-north coast, on September 12, 2014.
Deputy State Coroner Harriet Grahame has ordered counsel assisting the inquiry to file submissions by February 28, while the police commissioner's are due by April 29.
All other submissions must be filed by May 30, before responses are handed up by June 13.
The coroner will then set down a date to deliver her findings.
In November, the fifth batch of evidence to the long-running inquest focused on a 2021 police search for William, along with a theory he died in an accident before his foster mother disposed of the body.
The alleged motive was that the woman and her husband would lose custody of another child under their care if the death was uncovered.
The foster mother denies having anything to do with William's disappearance.
No evidence was presented that anyone had been seen moving William's remains.
Ms Grahame noted the lack of proof while admitting a report on the possibility wild dogs could have moved the body.
No one has been charged over William's disappearance and a $1 million reward for information stands.
A decade-long investigation has involved hundreds of persons of interest and dozens of searches.
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