The distraught mother of suspected outback murder victim Tanja Ebert says her daughter's two orphaned children "are the true victims in this tragedy".
Andrea Ebert arrived from Germany as the search continued for the 23-year-old.
Ms Ebert says it's hard not knowing what happened to Tanja but the family still has hopes she will be found alive.
"We worry about Tanja and Michael's two young sons, who are the true victims in this tragedy," she said in a statement read by police on Friday.
"Their well-being is our utmost priority, with Michael's family we share in their future."
Michael Burdon, father of the two boys aged one and three, killed himself last month as police began to investigate his wife's disappearance.
He remains the only suspect in her likely murder.
But Ms Ebert's family described the 41-year-old as a "wonderful" father.
"We do not feel hopeless," they said in the statement.
"It's our hope to find Tanja alive and well. We also grieve for Michael Burdon.
"We knew Michael as a wonderful father, a good friend and a sociable person."
On Friday, mounted police joined other officers at the family's 410 square kilometre sheep station near Mannahill, northeast of Adelaide.
But police said it was difficult to predict the result of the search given the remoteness and enormity of the property.
They have been searching old mine sites and other areas of interest on the property since Wednesday with the help of mining experts and specialist camera equipment.
The last time Ms Ebert was seen by people other than her family was on August 8 when she visited the SA Museum in Adelaide with her husband and sons.
As the family drove back to Mannahill, Mr Burdon told police she became agitated and got out of the car near Roseworthy, north of the city, and walked off.
But he did not report her missing. Another family member contacted authorities two days later.
Ms Ebert arrived in Australia from Germany several years ago and married Mr Burdon in February.
Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14.
