I am trying to locate my great great grandfather. He was born in Madrid Spain in the 1800's.Unsure about exact DOB. He migrated to Pto Rico?

The name has a strong connection with Petworth in Sussex, however I think the records on here are user submitted so could bias the sample.
https://familysearch.org/search/record/r...
There is a one name study of Nevitt which says that Nevatt is a variant
http://one-name.org/name_profile/nevitt/
They say it has probable Welsh origins and "Early records suggests that the Nevitt name was mostly located in Shropshire and Cheshire, later spreading to Lancashire, Staffordshire, Warwickshire. Also to be found in the early records in the city of London and Home counties."

You trace your family starting with yourself and working back one generation at a time, documenting everything you do. Surnames in themselves don't indicate your ancestry. You don't trace surnames.

Once you find ancestor on one of the rolls such as the Dawes roll or Cooper Rolls for some Choctaw then you have proof of Indian ancestry. Now unless you belong to a specific tribe Native Americans do not consider you one of them. Each tribe has its own criteria for membership. Also, there are no benefits. The tribes have some medical benefits and scholarship for tribal members who qualify. This does not mean every young tribal member will be considered for a scholarship. Some tribes require a few years of community service to the tribe for a young person to be considered for a scholarship.

Trace your family tree back, one generation at a time, until you come to someone on the Dawes Rolls or have accounted for everyone as an immigrant from Europe.

A DNA test, which runs $100 or so, will tell you if you have NA "Markers"; not tribe or how far back, and the percentage will be a rough approximation, but that there is some "Indian blood" in your veins.

If you are African-American, the family legend that great great grandma was a Cherokee Princess is, 99% of the time, false. (Well, 100%, because the Cherokees didn't have royalty, but there is at least one person in the USA who is AA and whose GGM was Native American. Probably not you, though.)

(Search, in this category only, for "Cherokee" if you don't believe me; people ask about it every week.)

Mackay Name Meaning
Scottish and Irish: see McKay.

Mckay Name Meaning
Scottish and northern Irish: Anglicized form of Gaelic Mac Aodha 'son of Aodh', an ancient personal name meaning 'fire'. Etymologically, this is the same name as McCoy.

Bryning Name Meaning
Not found

Staniland not found either.

Source for all: Dictionary of American Family Names ©2013, Oxford University Press

Here's how many records I found on
https://familysearch.org/search
(free) for each

320,520 results for Name: Mackay
895,211 results for Name: Mckay
(I'd bet large sums at long odds that many of your MacKay ancestorss got recorded as McKay part of the time.)

8,315 results for Name: Bryning
18,105 results for Name: Staniland

Grandfather isn't very far back, for genealogists. You Brits have a handicap, too; your census must remain private for 100 years. Over here it's only 72, so we can find people on the 1940. Your latest one is 1911.

Since I spent a lot of time, typing out an explanation before.. I will just cut and paste it. Apparently, you failed to understand ANY OF IT.
there is nothing to be confirmed or not confirmed. Like many others, you got sucked into the "surname origin" game, that claims your family "comes" from the origin of your surname. These sites are completely useless, since they lead you to do what you are "attempting" to do... that is, relate a surname to the origin of a person.
Your mother's father was born, where he was born. His father was born in one location. For all you know (since you are sidetracked with false info), your gr gr grandfather may have been born Hernadez, and adopted by Mr Mares (who probably was not from France either). Your mother's coloring could easily come from the female ancestry ..NONE OF THOSE being born with the Mares surname. Genes don't have surnames.
Please take a hard look at this list..
https://familysearch.org/search/record/r...
you can see... Mexico and Spain are the top of the list of where the last name is found in valid records.
France isn't even ON THE LIST.
Not to hurt you.. but your research seems very flawed.