I think it's possible that the 2 Mary's were not living together in the 1910 census, making it quite impossible to determine which of the many Mary Smith's are the right ones. I tried looking at the census ED numbers for the streets you had from the marriage record and learned that they both are not in the same ED #, at least not in Brooklyn. I looked again at the web site italiangenealogy, and in their death index is an Alfred Hilton died 12/22/1915 in Manhattan, age 30. There are many Martin Smith's on that index. Well at least you are making some headway. Resources keep coming on-line which help us all in our searches, and give us something to look forward to.