Mere Riripeti Whakaraurahi Down (Whakaraurahi Raharuhi) - Seeking more information

Hello, Mere is my 3 greats grandmother, I would like to know more about her whakapapa and her hapu. I have not been able to find this online as you can imagen its very hard to know where to start. I would like to register with my Iwi but dont have enough information, so if anyone can help me it would be much appreciated, Shane Floyd