The Silvestri Family, Catania, Sicily, Italy
Concerning the Silvestri guitars I found this information:
"One of the main reasons for importing steel-string acoustic guitars into Britain in the 1950s was the demand for louder instruments, as the lighter nylon-string Spanish classics failed to deliver a groundbreaking sound in the folk, skiffle and rock & roll boom of the time. There was also a further UK import embargo on US instruments until June 1959 which meant that almost all guitars shipped to the UK came from Europe, mainly produced in Germany, the Netherlands and Italy.
Originally best known for mandolins and violins, the Italian luthiers and instrument makers had also developed expertise in producing high-quality Gypsy-Jazz guitars in the 1930s - 1940s and were ideally placed to produce cheaper to mid-priced steel-string acoustics, to produce salon-style guitars, which were in high demand in the 1950s.
The Catania instrument makers of Sicily were the prominent producers of these guitars 'Catania Carmelo' and 'Ermelinda Silvestri' were the largest volume producers of the time. The Silvestri company was founded in 1891 and changed its name to 'S. Sgroi Silvestri'."
According to old Italian family books, a man named "Santi Sgroi" was born in Catania in the year 1870 and married an "Ermelinda Delfina Maria Silvestri" who was born in San Martino Carano (near Modena) on February 10, 1878. As profession "luthier" will be mentioned. So that sounds like a match.
They had 5 children, Alarico (Rico) Sgroi (born 1899), Salvatore Sgroi, two more boys and a girl Maria Liboria Sgroi who lived only 1 year from 1901 to 1902.
In address books from that time, the family address is listed as:
"via Ventimiglia 202, Catania" under "mandolin makers".
The company "Ermelinda Silvestri" was founded in 1891.
There was also a relationship with Rome (Roma), maybe she started there as a guitar builder?
https://www.mandolincafe.com/forum/attachment.php?attachmentid=70002&d=1300818859
The later label:
https://images.reverb.com/image/upl...90,w_620/v1520705460/cyhqpwoxh2bxrcrjhhoz.jpg
And:
https://5.allegroimg.com/original/0caba3/64f5bd6347ccbfb1d0939c345095
Santi Sgroi's own brand at the time was "S. Sgroi Mancuso", founded shortly before in 1888.
Example of a "S. Sgroi Mancuso" label:
https://www.mandolincafe.com/forum/attachment.php?attachmentid=128227&d=1419997332
It seems that at one point they also had a shop in Naples (Napoli):
https://images.reverb.com/image/upl...90,w_620/v1525872326/issefm6pzxuwuqaphjga.jpg
As for the Mancuso part: Santi Sgroi's mother was a native of Mancuso. Santi's father Salvatore married Liboria Mancuso in 1858.
So when "S. Sgroi Mancuso" and "Ermelinda Silvestri" merged, the new company was named "S. Sgroi Silvestri".
It seems like always the name of the father and mother got put together and that is why I suspect that "S. Sgroi Silvestri" actually started when a son of theirs took over the business, probably their aforementioned son Salvatore? But there were two more sons whose names I couldn't find, maybe one of them also started with an "S".
There is a very interesting label with the new name "S. Sgroi Silvestri" with the word "già" underneath, meaning "already", so the label showed that the new company is the merger of both former company names.