Couple Gail and Don Patterson, both 70, died in hospital after eating lunch at a Leongatha home in Victoria's southeast on July 29.
Mrs Patterson's sister Heather Wilkinson, 66, also died after the meal while her husband, Baptist church pastor Ian Wilkinson, remains in hospital in a critical but stable condition.
Police believe all of their symptoms were consistent with being poisoned by death cap mushrooms.
A representative of the Patterson family on Wednesday confirmed a public memorial service will be held for Gail and Don Patterson on August 31 at Korumburra Recreation Centre.
"The Patterson family has expressed their deep gratitude for the outpouring of love, support and understanding during this challenging time," a statement read.
"In keeping with Don and Gail's wishes and character, the family has chosen to commemorate their lives in a manner that reflects their values and the love they shared with their community."
A private burial was held earlier this week with only close family members in attendance.
The Pattersons' daughter-in-law Erin Patterson is considered a suspect as she cooked the lunch that is believed to have led to the deaths.
Police have not provided any updates on their investigation.
10°C