Family killed 19 days after daughter born

Abbey Forrest longed to be a mother. She and her partner Inderpal Sohal wanted four children.

They were parents for 19 days before their lives and that of their baby girl Ivy were cruelly taken.

"Their last breaths will haunt me to my dying days," Elizabeth Forrest said.

She lost half her family in December 2020, when Jenny Hayes set fire to a Point Cook townhouse.

Ms Forrest, 19, and Mr Sohal, 28, were asleep upstairs with baby Ivy in their newly rented townhouse and could not escape. They died from carbon monoxide poisoning.

Mrs Forrest still calls her daughter's phone, knowing she won't answer, and sometimes she pretends the young couple have taken their daughter to visit Mr Sohal's family in India.

"I know it's not true but on the hard days it's easier to comprehend than what really happened," she told Victoria's Supreme Court on Monday.

Leah Maffescioni said they held a 21st birthday party for her best friend Ms Forrest at the weekend and the pain of having to sing happy birthday to only a picture of her was indescribable.

Mr Sohal's sister Harpreet Sekhon couldn't bear to tell her children the family had died, and recalled her young son seeing a photo of them in a newspaper.

"He innocently asked if they were famous," she told the court.

Her father died four months after the family's deaths, but he died in spirit on the day of the fire, Ms Sekhon said.

Hayes was furious about a sexual encounter ending badly when she set fire to the townhouse just before 2am on December 2.

The downstairs bedroom was free to be used by one of Mr Sohal's friends, who had hired Hayes, a sex worker.

Services were provided by Hayes and paid for by the friend, but there was a dispute and the friend left.

Hayes claimed she was raped by him and he had taken money from her handbag, sending him a series of angry texts, including telling him she would set fire to his house.

She set fire to the bed and took photos as the room caught alight. The blaze quickly spread and even as she drove away, she took another picture.

"I'm so sick of people thinking they can do this s*** to me and nothing happens to them," she sent in a text.

Mr Sohal, who was born and raised in India, had been living with the Forrest family in Geelong during Melbourne's COVID-19 lockdowns.

Ms Forrest, an aspiring paramedic, fell pregnant during her gap year. She longed to be a mother, Mrs Forrest said.

Her father Alan paid tribute to Ms Forrest's cheekiness and competitive spirit, revealing he sobs through Sunday family dinners without her.

"Our hearts are broken forever," he said.

Hayes pleaded guilty to three charges of arson causing death.

"It was only a little flame on the bed," she told police after her arrest.

Hayes maintains she didn't know there was anyone else in the house.

She has dealt with homelessness for most of her life and suffered significant abuse as a child and into adulthood, the court was told on Monday.

Her borderline personality disorder reduces her capacity to regulate emotions and likely would have contributed to her disproportionate response to being ripped off, a psychologist suggested.

The victims' family intends to seek compensation for the fire through civil action.

The family is being represented by John Herron, whose daughter Courtney Herron was murdered in 2019.

The hearing will continue on Tuesday.