The Children's Commissioner will not back a register to monitor all children despite a coroner saying it will save lives.
Moko died in 2015 after prolonged abuse by his two carers, Tania Shailer and David Haerewa.
He was kicked, slapped, bitten, thrown and stomped on.
When he began soiling himself, he had faeces rubbed in his face as punishment. He died of a ruptured bowel and a head injury.
Ten years ago after the killing of Nia Glassie, he recommended that all children be registered from birth with government agencies. Another 94 children have died in that time.
Dr Bain says whatever the cost, child abuse has to be stopped and a register could save lives.
He says agencies like Well Child Tamariki Ora and Children's Teams already exist, and it would be pointless to "reinvent the wheel".
"That's why using and expanding existing services is a better immediate first step, and ensuring that they're well trained."
Judge Becroft says to end violence against children, government agencies needed to work alongside highly trained community agencies.
'We have children dying'
But Merepeka Raukawa-Tait, the former head of Women's Refuge, says the equivalent of three classrooms of children have died since Nia Glassie.
"We can't be precious in this instance, we have children dying, and they're dying regularly.
"This is a major recommendation out of a coroner's report, surely this time it's going to be acted upon."
She says community groups would need to deliver services because families did not trust government agencies.
Arama Ngapo-Lipscombe is the lawyer for Moko's mother Nicola Dally-Paki.
She would back a register but adds a word of caution.
"There will be a fear that it's used to prejudge, prejudice, predetermine and that will lead to professionals making judgements without taking into account a person's circumstance.
"There is a risk they will look at the register and profile them."