Yesterday, coroner Peter Ryan grilled CYF chief social worker Paul Nixon about what the agency was doing to identify vulnerable children in similar circumstances.
The inquest had heard how CYF became aware of Hail-Sage only after a doctor raised concerns about her health shortly before she died.
This was despite her mother being a domestic purposes beneficiary and two of her children already being in CYF care because of safety fears.
Mr Ryan said an apparent lack of information-sharing between government agencies "seems to me something that could be strengthened as a safeguard for someone falling through the cracks".
"This would also seem something that would be reasonably easy to do."
Mr Nixon said there were a number of initiatives making a difference, including a memorandum of understanding between CYF, police and Work and Income.
But he conceded that an interpretation of the privacy laws was "affecting the way people perceive their mandate to share information".
"What we don't have yet is one unified approach in the country because of questions about the privacy laws."
He said mandatory safety assessments were now in place and at a social worker's discretion, at-risk children could be taken away after a check on their living arrangements and circumstances.
But asked if he was satisfied the amended measures would prevent something similar happening again, Mr Nixon was uncertain.
He said quality early preventive services had an effect on identifying risk in Britain but children were occasionally missed.
"With child abuse it's hard to predict; it's not an exact science ... With young babies it's no different. The state tries to strike a balance with supporting families where they can and protecting children when the needarises."
Outside court, Hail-Sage's mother took a swipe at CYF, saying they "didn't do their job" and had never contacted her to confirm her daughter's birth or living circumstances.
"I have never tried to hide that I had children and CYF - if they were doing their job - would have picked up that I had two more children," said Ms Percy.
"They never attempted to investigate me having other children."
Ms Percy and Mr Wilson-Minimita are seeking the return of her son and his son but CYF Midlands regional director Greg Versalko said he "can't foresee" the children being given back because of ongoing concerns about their safety.
Desi Walker, Ms Percy's sister, said her family had sought closure but were left without it.
In a tearful submission, she said her little niece's life had been "fully funded by the taxpayer".
"All of New Zealand had a vested interest in this child ... Hers was a future full of possibilities."
Matamata-Piako police sub-area commander Rod Carpinter said if any of the evidence presented at the inquest showed some criminal responsibility, police could lay charges.
But he said the investigation into Hail-Sage's death had ended because there was not enough evidence for the matter to proceed to the courts.
A Families Commission report released last month said inadequate systems between agencies were putting vulnerable children at risk of abuse. It called for better information sharing between government departments and enhanced reporting by health professionals to safeguard at-risk children.
Mr Ryan has reserved his findings.
