Coroner Alexander Ho was expected to deliver his findings in Invercargill on Friday, but in a recently released minute he said he "very reluctantly" abandoned the date.
In 2019, Lachie was found 1.2km from his Gore home, face up in an oxidation pond.
Police quickly concluded the boy had drowned, but later confessed they "missed some steps" in the investigation.
Two phases of a coronial inquest into Lachie’s death were held last year.
Coroner Ho had delivered his draft findings to interested parties and gave them until May 16 to respond.
Two days prior, lawyer Anthony Woodhouse told the court he had recently received instructions to assist Jonathan Scott — Lachie’s half-brother, now aged in his 20s.
At the inquest, Max Simpkins, lawyer for Lachie’s father Paul Jones, accused Mr Scott of being involved in Lachie’s death, including by putting his body in a freezer.
One witness alleged Mr Scott confessed playing a role in the boy’s death.
The woman said her friend told her: "Johnny was the one that threw his wee brother into the pond".
"He said he grabbed him, picked him up and biffed him in," she said.
Mr Scott was not represented by a lawyer at the inquest, but vehemently denied any involvement in his half-brother’s death.
Mr Woodhouse said he had some catching up to do, and asked for an extension of time to file his response to the draft findings.
Coroner Ho granted the request, before a second extension was asked for and allowed.
The minute also explained the police were gathering further information which was raised as an issue in the draft findings.
The specifics of those inquiries were suppressed by the coroner.
The police’s results could not be provided until two days before the findings were expected to be delivered, and the final hearing was now scheduled for June 13.
