Annabelle Falkholt, 21, died at Liverpool Hospital in Sydney on Friday morning.
Her Home And Away star sister, Jessica, is still fighting for her life in an intensive care unit following the horrific car crash that three days ago killed both their parents.
On Stephen’s Day, Lars, 69, and Vivian, 60, died instantly when they were hit by another car that veered onto the wrong side of the road near Ulladulla, New South Wales.
A passenger travelling in the other car was also killed in the crash.
“Annabelle passed away this morning, we knew what was happening so family were with her,” a relative told DailyMail Australia.
“Her and Jessica had such a strong sister bond. They are seriously close sisters. I feel Jessica would have known her sister has passed.”
Jessica, 28, is best known for her role as Hope Morrison in Home And Away; she appeared on the famous Aussie soap in 2016.
Annabelle’s boyfriend, Jordan Brohier, paid a heartbreaking tribute to the “love of my life” on Facebook early on Friday morning.
He wrote: “I’ve never met such a kind, gentle soul and this world is at such a loss without this beautiful angel.
“The 3 years I knew her were the best years of my life. I’m so thankful for every second I got to spend with my baby.Annabelle Falkholt
“I just keep hoping that I’ll wake up from this terrible nightmare and see her gorgeous eyes looking back at me.
“She was the most amazing girl I’ve ever met, loved by everyone that came in contact with her.
“Even though I would of loved to have spent the rest of my life with her, I am happy that she is pain free and smiling down on all those who were lucky enough to have her in their lives.”
Jessica is being treated at St George’s Hospital in Sydney.