Whanganui politician, negotiator and organiser Ken Mair will marry his long-term partner, Moana Hawea, at Whangaehu Marae on January 5.
The two have seven children between them - Mr Mair four from his first marriage and Ms Hawea two from hers. They also share a daughter.
At least 400 people would attend the celebration, he said.
Mair is a vice-president of the Maori Party and MP Te Ururoa Flavell is to be best man. Also present will be party president Pem Bird, and Ms Hawea's auntie, Maori Party co-leader Tariana Turia.
They will be joined by kuia and kaumatua from Ngati Apa and Whanganui, and many others.
Whangaehu is Ms Hawea's home marae and Mr Mair also has connections to it, although his connections with the Whanganui River are stronger.
He was one of the organisers of the 1995 occupation of Pakaitore/Moutoa Gardens and applied to the New Zealand Geographic Board to change the spelling of Whanganui. He's now a director of Te Ohu Kai Moana and other boards, a negotiator of the Whanganui River claim and the chairman of the Tupoho Whanau Trust.