More than 100 people attended the plaque unveiling at the Murtoa-Horsham Road property which acknowledges the family's custodianship of the area for five generations.

The work of Frank Delahunty, who died last year, was highlighted due to his 74 years running the property.

Eldest son and Member for Lowan Hugh Delahunty said the family was proud to be acknowledged.

"Family history is very important to us," Mr Delahunty said.

"We were especially proud that so many people came to the launch. We only expected to see 50 or 60 people.

"The homestead of Erin's Vale is currently leased by a private person and the land leased to other members of the Delahunty family. So we felt it was important to mark the family's history in the area."

James Delahunty arrived in Victoria from Tipperary, Ireland, in 1865, with his mother Mary and brother Roderick in 1866.

The brothers selected adjoining blocks in 1871 and called the land Erin's Vale.

They quickly expanded, buying neighbours portions of Avalon Park and Longerenong estates. Roderick's sons Jack, Jim and Mick developed the well known properties of Templemore, Roscrea and Erin's Vale.

"Our grandfather Mick, a Light Horseman in World War I, married Lily in England in 1920 and returned with her to the Erin's Vale farm, with his father Roderick, uncle James and sisters Mary and Bridget," Mr Delahunty said.

"Mick and Lily's seven children grew up there - daughters Joan, Elizabeth, Dorothy and Maureen and sons Frank, Lawrie and Rody worked the property."

Mr Delahunty said the heritage plaque was in gratitude for Frank, who died in 2008, and Kath, who died in 2006, Delahunty's care of Erin's Vale from their six children, 17 grand children and five great- grandchildren.