A man and woman, both 19, were found dead of apparent gunshot wounds after South Australia Police were called to the property northeast of Millicent on Saturday night.
A 46-year-old man was arrested without incident and has been charged with two counts of murder.
He is the father of the 19-year-old man, SA police confirmed on Sunday.
It’s likely the man will face Mount Gambier Magistrates Court on Monday.
Police said the couple, who are from Adelaide, appeared to be visiting the property.
Detectives and forensic experts travelled to the area on Sunday morning and are expected to remain at the crime scene for the entire day.
No other offenders are wanted in connection to the incident.