Hannah Clarke and her three young children Aaliyah, Laianah and Trey were killed by her estranged husband Rowan Baxter, who doused their car with petrol and set it alight in February 2020.
Baxter killed himself at the traumatic scene in the Brisbane suburb of Camp Hill.
The crime shocked the nation, and was central to the recognition of coercive control as a feature of domestic and family violence behaviour.
One month after the murder of their daughter and grandchildren, Hannah Clarke's parents Sue and Lloyd launched the charity foundation Small Steps 4 Hannah.
The Clarkes worked tirelessly to raise awareness of the features of coercive control, which include surveillance of a partner's movements, isolating them from friends and family and monitoring communications.
Baxter was subject to a DVO after kidnapping daughter Laianah on Boxing Day 2019. In January 2020, the order was varied, giving him full access to his children less than two months before he murdered them.
He is alleged to have subjected Hannah Clarke to years of physical, emotional and financial abuse.
An inquest found he also photographed her movements, placed recording devices around her house, monitored her telephone usage, and attempted to prevent her from seeing her family.
Sue and Lloyd Clarke campaigned for standalone laws against coercive control, which passed the Queensland parliament in May 2025. The legislation is informally known as "Hannah's Law".
The offence carries a maximum sentence of 14 years in prison.
Small Steps 4 Hannah chair Mark Woolley said the fight against coercive control and domestic and family violence was ongoing.
"The Small Steps 4 Hannah Foundation continues to lobby for law reform and to fund meaningful support for families in need," he said in a statement.
"Our wonderful founders, Sue and Lloyd Clarke, have announced their intention to reduce their workload in an effort to ease the personal toll this journey has taken on them.
"However, Sue and Lloyd are tireless champions for the cause and they are going to remain closely involved as directors of the foundation they started in memory of Hannah and the children."
The statement said the foundation was financially secure and would continue to pursue the Clarkes' vision for an end to domestic and family violence.
"We look forward to the day when an organisation such as ours is no longer needed," Mr Woolley said.
"But sadly it is, and we will continue the fight."
Ourwatch.org says a woman is killed every nine days by a current or former partner in Australia.
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Lifeline 13 11 14
Men's Referral Service 1300 766 491
