Ismalia Davenport was born in Kaiapoi, the daughter of Tini Arapata and John Driver Tregerthen/Tirakatene. She was educated at Kaiapoi Borough School. She moved to Wellington and worked as a secretary for her brother, Sir Eruera Tirikatene, who was Member of Parliament for Southern Māori. In 1936 she married Poai Hemi Manahi, and raised their twelve children in the family home in Woodend which still stands proudly today. Poai Manahi was the Senior Minister for the Ratana Church in the South Island and the Chatham Islands. After his death in 1986, Aunty Jane became Awhina Runanga of the Ratana Church, a position she held until her death. In this role she made annual visits to the Chatham Islands and to Ratana Pa. Aunty Jane and Poai worked closely with Te Wai Pounamu Morehu Silver Band (the physical name), which has the spiritual name Te Whaea o Te Katoa. This is the seventh and last Reo of the Ratana Church and the only Reo in the South Island. The Reo accompanied Aunty Jane and Poai to marae, church services, and old peoples’ homes and made people happy through music and Māori culture. She taught instrumental music for people in the band and was formerly a choirmistress and Sunday school teacher in the local Ratana church. She worked with Kohanga Reo around Canterbury and taught te reo Māori at various Canterbury schools. Aunty Jane was kaumatua of a number of organisations including Queen Mary Hospital in Hanmer, the Canterbury Area Health Board and the Justice Department in Canterbury. She was Patroness of the Māori Wardens and was associate chaplain of prisons in Canterbury; she worked particularly with the women’s prisons. When the government funding for Rehua Marae ceased in the 1980s, Aunty Jane and Poai moved on to the Marae to assist the trade trainers in conjunction with the Methodist Mission. She was the chairperson of the Rehua Marae until her death, and was associated with the Council of Māori Elders and Māori Women’s Welfare League. She became a JP in 1990. She received a certificate of appreciation from the Rangiora District Council in 1989, was awarded the OBE in 1990 and won the Kingi Ihaka award. Aunty Jane worked in both the Māori and Pakeha worlds and "treated everybody the same": Māori, European or whomever. She was one of the few Kai Tahu women who spoke the Kai Tahu dialect fluently from her childhood.
- Conversations with Te Kahurangi Manahi and Pilot Manahi, August 1998.
- "1990 Queen’s Birthday Honours." Te Iwi o Aotearoa 34 (1990): 20.
- Women of the Waimakariri. Ed. P. J. Wood. Rangiora, N.Z.: The Waimakariri District Women’s Suffrage Centennial Committee, 1993. 9-10.
- "Te Kōtuku - Te Manu Wairua o Te Toka/White Heron - The Spirit Bird of the South." Written in Māori with English translation by Aunty Jane Manahi. The Penguin Book of Contemporary New Zealand Poetry/Ngā Kupu T˚tohu o Aotearoa. Ed. Miriama Evans, Harvey McQueen and Ian Wedde. Auckland, N.Z.: Penguin Books, 1989. 326-327.
- In this tribute to the kōtuku, the poet reflects on its birth ‘deep within the forest / of Okarito’ and its emergence and flight as ‘the beautiful / white heron / Spirit Bird of the South’.
- "1990 Queen’s Birthday Honours." Te Iwi o Aotearoa 34 (July 1990): 20.
- Te Karaka: The Ngāi Tahu Magazine Ngahuru 1995.
- Women of the Waimakariri. Ed. P. J. Wood. Rangiora: The Waimakariri District Women’s Suffrage Centennial Committee, 1993. 9-10.
- "He Maimai Aroha." Mana: the Māori News Magazine for all New Zealanders 10 (1995): 10-11.
- "Obituary: Ismalia Jane Manahi." Press 8 Sept. 1995: 18.
- "Whakahonore ki a Jane Manahi." Te Karaka: The Ngāi Tahu Magazine Raumati/Summer 1996.