A four-year-old girl died after crashing into objects while being forced to ride a motorbike as her mother filmed her, a South Australian court has heard.

Supreme Court Justice Trish Kelly commented on the child's obvious fear in video footage shown to the court of her opening Christmas presents just days earlier.

Ashley Jean Polkinghorne and her partner Benjamin Robert McPartland are awaiting sentencing for manslaughter by criminal negligence over the death of the woman's young daughter Chloe.

The girl was repeatedly put on a 50-kilogram motorbike in the backyard of the family home at Ingle Farm in January 2012 and the mother and partner filmed the girl crashing into objects.

The Supreme Court was told the girl suffered severe injuries and was so swollen and bruised when taken to hospital that some other family members could not recognise her.

During sentencing submissions, Justice Kelly made particular reference to the video screened to the court of the child on her last Christmas Day.

"The footage I've seen of that child opening her Christmas presents is one of the most chilling pieces of footage I have ever seen of a child opening Christmas presents. It was utterly chilling," she said.

"This was a plainly frightened child on Christmas Day."

The court heard Chloe sometimes clung to her grandmother at the end of visits and pleaded not to be sent back home to Polkinghorne and her partner.

It was told the child had confided to a family member she was "scared" of McPartland.

Justice Kelly said both Polkinghorne and McPartland had sought to blame each other for the girl's death after she crashed.

Grandmother held girl as she died in hospital

In a victim impact statement which was read to the court, Polkinghorne's mother, Belinda Valentine, said her granddaughter's death had "shattered" the lives of other family members.

She told how she rushed to hospital and held her granddaughter as she died.

"She was like a broken doll lying in the bed in hospital with tubes and wires coming out of her," Ms Valentine said.

"At first I couldn't recognise her, she was so swollen and bruised and broken. It was horrific and unbelievable.

"They say people look peaceful in death. Chloe didn't. She looked battered and bruised and alone."

Ms Valentine says the inconsistent accounts Polkinghorne and McPartland gave to authorities after Chloe's death only made the family's grief worse.

"When those circumstances are shrouded in secrecy and lies it makes the depth of feelings such as anger, sadness, regret and frustration intensify beyond reason," she said.

The court heard Polkinghorne and McPartland left the hospital as soon as Chloe's life support was turned off and were not there at the time of death.

It was told the pair were smoking and laughing outside the hospital and were overheard saying that they could not believe police had not found their cannabis stash during a visit to the house.

Polkinghorne cried and shook her head at times during the latest hearing.

Judge questions if it were more than stupidity

McPartland's lawyer, Anthony Allen, told the court it was a tragic case and his client accepted joint responsibility for Chloe's death.

"This case ... is really stupidity at its highest level that's had devastating consequences," he said.

Justice Kelly questioned that statement, saying the child was repeatedly made to get back on the motorbike despite her horrific injuries.

"Depending on what view you take, it's more than stupidity at its highest level, there is a sinister element to this. It's more than neglect," she said.

"She's virtually thrown onto the bike at one point."

Justice Kelly asked Mr Allen if the act of putting the child on the motorbike were a crime in itself, but he countered it was not.

Justice Kelly responded it "should be".

Polkinghorne and McPartland are due to be sentenced next week.