I can only post hints for thimgs foumd at ancestry´s or somewhere else in the internet as I am sitting here in cold old Germany. I understand that you keep to your real documents that you have in hands. It is tricky that there are Costa families with Porzuguese origin having nearly the same
A document to look for is a death certificate for Nicholas´ possible ( probable from my point of view) mother Angela. Here we have a matching(1880 census 37 years of age)death published in San Francisco morning call http://www.jwfgenresearch.com/SFCall/6900-33.htm
death in 1896 age 53.
I think there is a connection to a Podesta family I found this surname before but I do not know now where.
we have John Costa & Co and an Antonio Podesta. In 1877 John Costa alone http://www.sfgenealogy.com/sanfranciscodirectory/1877/1877_3...