'Her brain is like a Ferrari in that you can make everything look all right but you won't know until you turn the ignition on whether the engine is going to start,' he said.
Annabelle Falkholt, Jessica's little sister, was rescued from the crash alive but later died in hospital.
The sisters parents, Lars Falkholt, 69 and Vivian, 60, also passed away when their vehicle collided with another on the Princes Highway on the New South Wales south coast.
The third person killed by the crash was 50-year-old Craig Anthony Whitall.
