The girl was one of 15 people injured in a five-vehicle crash on the Great Western Highway at Wallerawang, 15km north of Lithgow, on December 30 that claimed the lives of two men.
An eastbound Isuzu D-max towing a motorcycle trailer collided with a westbound Toyota Hilux before the Toyota struck a Hyundai Tuscan, causing it to leave the roadway and trapping its occupants.
The Isuzu struck a Kia Carnival head on and a caravan-towing Nissan Patrol, travelling behind the Isuzu, struck the trailer.
The Isuzu driver, a 42-year-old man, and the Kia driver, a 49-year-old man, were trapped and died at the scene.
More than a dozen others were injured, including a 41-year-old woman and five children aged five to 15 in the Kia.
One of its passengers, an 11-year-old girl, had died at the Children's Hospital in Westmead, police confirmed on Saturday.
More than 80 rescue personnel including police, paramedics, Fire and Rescue NSW, Rural Fire Service, VRA Rescue and the State Emergency Service attended the crash scene.
Police will prepare a report for the coroner.
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