The four-person panel set to investigate the best structure for the future governance of Wellington councils was announced on Wednesday.
The panel has been organised by Porirua City Council and Greater Wellington Regional Council, although other councils in the Wellington region were invited to take part.
The three Wairarapa councils declined as they were already undertaking their own study on options for future governance, but previously said they were happy to share their findings.
The terms of reference that the panel are to investigate were also finalised by the councils on Wednesday.
The panel consists of Sir Geoffrey Palmer, Sue Driver, Sir Wira Gardiner, and Bryan Jackson.