Patterson, 49, is charged with three counts of murder and five of attempted murder, according to court documents.
She did not seek bail, and the case will next be heard in May 2024. She has previously denied wrongdoing.
Don Patterson, his wife, Gail, and her sister Heather Wilkinson became ill and later died after the July 29 lunch in Leongatha, a small rural town around 135 km (85 miles) southeast of Melbourne.
Local media reported Don and Gail Patterson were the parents of Erin Patterson's ex-husband Simon Patterson, who was also present at the lunch.
Simon Patterson is listed in court documents as the alleged victim in four of the accounts of attempted murder, including three separate incidents in 2021 and 2022.
The alleged victim in the fifth count, Wilkinson's husband, Ian, a pastor in a nearby town, became seriously ill after attending the lunch and was released from hospital in September.
Police said in August the symptoms of the victims were consistent with mushroom poisoning. Dean Thomas, one of the detectives involved in the case, told a news conference on Thursday the investigation was continuing.
The mysterious deaths have gripped Australia, where deaths from eating mushrooms are relatively rare.
Months before the deaths occurred, the state of Victoria where the incident took place released an advisory warning would-be foragers not to pick or consume wild mushrooms unless they were experts.
"Anyone who collects and consumes wild mushrooms of unknown species is putting themselves at risk of potential poisoning and serious illness," the state's health department said.
The advisory noted that the "Death Cap" mushroom growing in the state was poisonous enough to kill an adult human, while a second, the yellow staining mushroom, was the cause of most poisonings as it looked similar to edible wild mushrooms.