Middle and upper Whanganui River Maori groups are seeking changes to the river's settlement bill, making them full iwi rather than hapu.
The groups include Ngati Uenuku, Tamahaki and Taumarunui's Ngati Haua.
The Uenuku Charitable Trust supported Ngati Haua speakers' presentation on the matter to the Maori Affairs Select Committee in Wellington on Monday.
The committee is considering the Te Awa Tupua bill before it has its second readng in Parliament.
The Uenuku Charitable Trust was formally mandated to represent people from Central Whanganui's Te Korowai o Wainuiarua in Treaty of Waitangi negotiations on June 20 this year.