The actress, who was best known for her role in Home and Away, had her life support switched off at St George Hospital on Thursday, and a relative told Daily Mail Australia: "We made sure Jess wasn't alone and her friends were able to be there with her".
The decision to end life support came the day after the funeral for her parents and sister.
Ms Falkholt, 28, remains fighting for her life in Sydney's St George Hospital after the accident.
A message on the show's official Twitter feed said: "Rest in peace, attractive Jessica".
Police continue to investigate the crash, which also claimed the life of 50-year-old Craig Whitall, who was driving the other vehicle and died instantly.
Their parents died at the scene, and Annabelle died as a result of her injuries on December 29.
Doctors have performed multiple surgeries on the 29-year-old Falkholt - including reportedly removing a portion of her skull and one of her kidneys - in an effort to save her life.
The drama's broadcaster, Network Seven, said of Jessica in a statement last month: "Although her time on set was brief, once a part of the Home and Away family, always part of the family".
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According to The Telegraph, Whitall's driving record includes four jail sentences for traffic offenses, a nine-year driving ban, and "at least 10 convictions for driving while disqualified".
Paul Ponticello, brother to Vivian and uncle to Jessica, said he "always thought we would grow old together".
"It's a day that will be hard to erase from our memory", the Daily Mail reported Paul saying of the tragic accident.
He also spoke about the love between his sister and brother-in-law: "They are together and always will be".
Lars, Vivian, Annabelle and Jessica Falkholt.
The young actress had previously appeared as Hope Morrison on Home And Away in 2016.
Mr Whitall, a P-plater, was reportedly driving home from a methadone clinic when the collision occurred.