Five generations of the family from throughout New Zealand and Australia will take part in an official unveiling of a new gravestone at the Alexandra Cemetery, as well as other activities centred on their Irish-born ancestors.
Brian Meagher, of Springwood, New South Wales, Australia, said family members would visit the McGettigans' original Fruitlands farm and homestead this morning.
Those involved in the reunion ranged in age from mid-80s to young babies, he said.
The family will have lunch at the old Fruitlands gallery, which McGettigans managed at one time when it was a boarding house.
This afternoon they will visit the cemetery in Alexandra, where Patrick and Mary McGettigan were buried alongside Mary's parents, John and Sarah McDonnell.
Mr Meagher, who is writing a book about the family history, said a new gravestone in reverence of the family had been made and would be officially unveiled at the cemetery.
Patrick McGettigan was born in Ireland, which he left in 1853 for Victoria, Australia.
While in Australia, Mr McGettigan heard land was to become available in New Zealand, and moved to Central Otago in the mid-1860s.
He was a major landholder at Fruitlands, which was known at the time as Bald Hill Flat. There he met Mary McDonnell, who was also Irish-born and had moved to Central Otago with her parents.
Mr McGettigan was initially a store-keeper during the gold rush, before moving into agricultural farming.
Involved in this weekend's family reunion is descendant and namesake Rev Patrick McGettigan, who is a Catholic Parish priest in Alexandra, as well as fellow Alexandra residents and descendants Joan Brown and Robert McGettigan.
Mosgiel resident Mervyn McGettigan will also take part.
The family first had a reunion in 1995, part of which took place in Central Otago.
Mr Meagher's book, From Ulster Ireland to Central Otago New Zealand: Patrick McGettigan and wife Mary McDonnell, is due to be published this year.
It would be the first published history of the family, Mr Meagher said.
