Before the 2015 reform, clause 9 required the Board, when a representative position became vacant, to appoint another person who in its opinion was qualified for the particular representative position. That wording makes each representative capacity legally distinct inside the same corporate trustee.
Some successions look strongly whakapapa-based. James Clendon Tau Hēnare explicitly succeeded his father Tau Hēnare on the Board in 1940. In the Te Rata position, Korokī's appointment was confirmed in 1934 “in place of his late father”.
But the rule was not simply hereditary descent from the named founder. The Te Rata office later included Hepi Te Heuheu, who represented the Māori Queen, and later holders connected to Kīngitanga. The legal constituency remained Māori south of Auckland. Likewise territorial positions such as North Auckland Māori or South Island Māori and Pākehā could be filled by people qualified to represent that population without being descendants of the original holder.
Succession preserved the representative capacity. The way a person qualified for that capacity could be whakapapa, institutional standing, territorial connection, public standing — or a combination.
The 2015 amendment formalised fixed terms but preserved the old architecture. Most strikingly, the combined Riri Maihi Kawiti position was split into four separate family offices. Parliament required appointments from the Hōne Heke, Maihi Kawiti, Tāmati Wāka Nene and Pōmare families and treated those appointments as if they had been made under the original deed.
That does not turn the offices into beneficial ownership or sovereign offices. It does show that the representative identity attached to each seat was not incidental. It was important enough for the deed to require continuity and for Parliament, more than eighty years later, to legislate around the original capacities by name.
Next evidential test: obtain the appointment and confirmation resolutions for every vacancy. Those minutes can tell us who nominated the successor, what evidence of qualification was presented, whether the represented people were consulted, and whether the Board treated whakapapa, electoral mandate, Kīngitanga authority or another criterion as decisive.
Sources: Parliament's summary of the original succession clause; James Hēnare biography; Korokī succession confirmation; Hepi Te Heuheu biography; 2015 Amendment Act.