I had earlier been working on the Keale line, and actually had a wonderful breakthrough a few weeks back, initiated by someon emailing about the Padekan line. They'd seen my work on behalf of a family in our ward (LDS word for congregation). In addressing her question I was looking at a common name the Padeakn 'ohana and mine share- 'Opunui. In looking to see a link (since the geni sight had a pedigree maintained by a very distant cousin through our Nu'uhiwa (Kaua'i) and Kela (Ni'ihau side) I found a wonderful transcript of an oral history.
So today when I saw the post abt the Manini-Keale family in the fb group for the Native Hawaiian genealogy Society, I got excited. Here is what I messaged the person who grandmother was Violet Kui- the niece of my direct line.
Aloha, these are the records that conflict regarding the name of Violet's mother who is from our Ni'ihau side of the family. The first is the marriage record for Charle S A Kui ( Father's Name: Keiki Liilii, Mother's Name:Kapewaiku Liilii) married to Emma K Keale. https://familysearch.org/pal:/MM9.1.1/FW8H-ZLQ

The other record is the 1920 census record where the family is listed as
SELF Charles Kui M 31 Hawaii
WIFE Mele Kui F 29 Hawaii
DAU Emma K Kui F 5 Hawaii
DAU Violet A Kui F 2 Hawaii
https://familysearch.org/pal:/MM9.3.1/TH-266-11009-122658-5?cc=1488411&wc=12019631
If you look at the actual image they are house 35, but her father and siblings are above under house 33. Just so you know her father was known as Keale Te Kaula (Keale the Prophet) here's a link to the story. http://www.oocities.org/moekeale2020/retrospective.htm

This ancestor was the author of Ua Mau (very well known spiritual song back home) http://www.oocities.org/moekeale2020/s-uamau.htm

The town of Ni'ihau was renamed Pu'uwai by him.
Here is a link I thought you might like. When I was young I spent time with our family from Ni'ihau (I never went there, only my brother) but they are some of my favorite memories. http://www.halaumohalailima.com/HMI/Pupu_o_Niihau.html

I do need to resolve if Violet's grandmother was Mele or Emma or maybe she went by both. Or maybe, as was the case in other locations of haole, that Mele was often just used as the female mother's name on cital stat records. Maybe a haole from an area like that who was the recorder put it like that. Probably doubtful since it was the census record.
Here is a public picture I got from ancestry.com posted by a Manini-Kui 'ohana member. I wish I could see it better. I feel like seeing the faces of my people.

This has some of their pedigree....http://thegreatmanini.org/tree14.html