Hello to both of you searching for Fierro as I have good news where they are buried as I have also pictures of their headstones.They are buried in St Johns Cemetery in Middle Village Queens co NY. Their headstone says Maria 1875-1948 and Vincent 1874-1951. On the same stone is listed a Mary Ciammalvo 1893-1968? hard to read.Their are two more Fierro stones beside it.I believe there are four plots and I have the section and plot numbers.
If these are your Fierro you can e-mail me and I will share my information.I have Fiore/Ferro + other spellings on the same surname and with their accents and so many could not read or write in the 1700's and 1800's, this is probably the reason clerical error.