Lars Falkholt, 69, and his wife Vivian, 60, were killed instantly while one of their daughters, Annabelle, 21, died from critical injuries three days later.

Their daughter and sister, Home and Away actress Jessica, 28, remains in a coma with severe head injuries.

The family had been driving home after a short trip to the South Coast when they were involved in a head-on collision on the Princes Highway south of Sussex Inlet.

The driver of the other car, Ulladulla man Craig Anthony Whitall, 51, was also killed in the crash.

Mourners converged on St Marys Catholic Church at Concord on Wednesday morning to pay their respects.

The deceased family members were described as the "dearly loved and cherished father, mother and sister to Jessica," in a funeral notice.

"Lars, Vivian and Annabelle will be deeply missed by Vivian's brother Paul Ponticello, his children Paul and Natalie, along with many relatives and friends both near and far," the notice read.

"In Sweden, Lars leaves behind his brothers, sister and extended family."

Vivian had Italian heritage.

Donations to cancer charity Redkite have been requested in lieu of flowers.

essical Falkholt has undergone several surgeries including the removal of a kidney and part of her skull and is in a coma, it has been reported.

In recent years Jessica found fame on the small screen as Hope Morrison in Home and Away, with the long-running TV soap paving the way for her feature film debut in the forthcoming supernatural thriller Harmony.

with AAP