Their lawyers told Victoria’s Court of Appeal on Tuesday that Arthur only implicated the duo in a bid to secure a lesser sentence for himself.
Arthur had changed his story dramatically during the case, pinning this on flashbacks about the crime, Christine Lyons’ barrister Christopher Carr told the court.
Arthur also denied this was so he could secure a shorter jail term for himself but this was implausible, Mr Carr added.
“[It was a] bare-faced lie designed by him to bolster his credibility,” the barrister said.
Arthur pleaded guilty to murder. He was initially jailed for 16 years but this was later increased to 22 years on appeal.
Christine Lyons was jailed for at least 23 years for attempted murder and murder.
Ronald Lyons, 46, who is not related to Christine Lyons, was jailed for 12 years, with a non-parole period of nine, for attempted murder and assisting an offender.
He also claims Arthur lied to save his own skin.
Arthurs, Ronald Lyons and Christine Lyons had been living together in the Bendigo suburb of Kangaroo Flat. Ms Kelly lived in a bungalow at the back of the property.
Christine Lyons could not have children of her own and wanted custody of Ms Kelly’s, who were then aged between 11 months and six years.
The Lyons fed her a cocktail of sedatives, beta-blockers, anti-nausea tablets, analgesics and antihistamines.
Ms Kelly did not die and two days later, Christine Lyons directed Arthur to try again.
Arthur bludgeoned Ms Kelly to death with a hammer and Ronald Lyons helped dispose of the body.
The appeal hearing continues.