Officers chased after the 22-year-old outside Liverpool Local Court after upgrading the charges against Johnson Kokozian, 20, over the horrific Friday night smash in Sydney's south-west.
He allegedly fled the scene after crashing a Mercedes-Benz AMG while travelling at nearly double the speed limit for the 50km/h zone.
Alina Kauffman, 24, and her 15-year-old brother Ernesto Salazar were killed in the crash just 200 metres from their Heckenberg home.
Police initially accused Kokozian of two counts of dangerous driving occasioning death, but those charges were upgraded to aggravated dangerous driving occasioning death due to the alleged excessive speed.
He was also charged with driving in a dangerous manner, negligent driving occasioning death, two counts of failing to stop and assist after vehicle impact causing death, as well as driving while disqualified.
Kokozian did not appear in court on Wednesday after being denied bail at the weekend.
A prosecutor told the court a brief of evidence would be served before the next appearance in November at Campbelltown.
Police have been looking for the other alleged occupants of the Mercedes following the smash after being told three young men fled its aftermath in a Volkswagen Golf.
They arrested the 22-year-old woman outside the court, while earlier on Wednesday a 21-year-old man was arrested at a home in Liverpool.
Both were being questioned at Liverpool Police Station, but no charges have been laid.