Catherine and Ximeng were both named as "Stars of the Week" at various times at Murrays Bay School this year, and have repeatedly won other awards at the school.
Murrays Bay School principal Ken Pembelton said the girls were "good kids" from "very respectful families".
Catherine had recently left to attend Milford School, he said.
Murrays Bay School Board of Trustees chair Sarah Bridge said the school had lost a member of its family.
"Ximeng was in year three in room 22 and was a lovely girl who was liked by all. Our thoughts and prayers are with the family at this time.
"Our thoughts and prayers are also with the Li family who previously attended Murrays Bay School."
The truck driver involved in the accident had been heading north, as was the Range Rover, and had attempted to stop, but was unable to do so and ended up on its side.
The Range Rover ended up on its roof in a ditch beside the south-bound lane.
Boogie boards and a sunhat were among debris strewn along the road.
The driver of the truck was taken to hospital in a stable condition with moderate injuries.
The accident came on the eve of the official Christmas road toll period which began at 4pm on Christmas Eve. It finishes at 6am on Monday, January 5.
Last year's road toll for the holiday period was seven but the official holiday period was three days shorter than this year.