Last night brought some more information! I received two emails in response to some posts I made on Ancestry that yielded some beneficial information.
1) Someone was able to send me a list of marriages of persons of color from the book Somebody Knows My Name by Barbara McGhee White. In the list is the marriage of my great-great-great-grandfather, James Koonce, to his first wife Susan. They got married in 1860 and I learned her maiden name – it was Craff.
2) I also was provided a link to an online database of deaths in the five boroughs of NY from 1891-1945. In searching that database, I think I have located the death date of my mother’s grandfather. There is only one Lewis Robinson listed that comes close to even being him! My uncle lives in NY, so he is going to the Municipal Archives sometime within the next couple of weeks to check it out and if it is him, get a copy of the death certificate for us. Maybe, just maybe, Lewis’ death certificate will have his parents names — here’s to hope. Furthermore, it turns out I am going to help contribute to the cause and will be helping add more records to the database! The coordinator is going to send me papers that I will help transcribe into Excel.