To access Genova you will need to go to a Family History Centre or affiliated library.
FOr records prior to 1867 in Chiavari you will need to access parish records via the Diocese.

Are you sure he is listed as her father and not the DICHIARANTE? Just becasue he declared the birth doesn't make him the father.
If his parents married AFTER his birth, then he would have been recognised as their son on their marriage record.

I just searched Ellis Island and although Vito Petruso comes up the manifest page is mismatched.
This was his original birth name assigned by the clerk at registration.

Adoption wasn't legal in those years. If Petruso is the surname of his foster father and they brought him to America then search for a ship manifest. It should show the 'real' name of your Grandfather. There are several towns with Borghetto as the first part. Google 'Comune di Borghetto' and try to ...

This is not something you search for in Google. You have to go to the State Archives of Vibo Valentia. You only nominate the 'frazione' Badia when nothing else works. Otherwise always use the Comune. Below is the link to the Stae Archives and below that is a copy of what penal records they have. htt...

You didn't say which town and there are several Archivio di Stato in Calabria. Once you decide which one then go to PATRIMONIO and in that area should be listed something like Corte di Assise. You don't get to search the documents. You have to write and ask them to search (if they have that service)...

Santa Lucia del Mela is a comune in the Metropolitan City of Messina in the Italian region Sicily, located about 170 kilometres east of Palermo and about 25 kilometres west of Messina. It is one of the largest comunes in the province of Messina. Wikipedia

Records will probably be found under MESSINA.

The State Archives records are all on line so if you didn't find what you need there then you need someone to go to the office (or the parish) and search for what you need. We have lots of experience in that town and the parish has a census that was written in 1832 and updated for the next 70 years ...

Keep looking. Names were repeated constantly and siblings often married siblings. The marriage record was created from their birth records so an error is not common. Check the parents names for the bride and groom to see if they match,

The marriage would have probably been between 1943-1946 if it actually occurred. This is in the area of privacy. Italy didn't have divorce until 1962 so if he remarried in the UK he would be considered a bigamist. To see if a civil marriage record exists you could request one from the City of Naples...

Start here.. https://www.familysearch.org/search/cat ... =753252-50

You need to be an a UK message board until you track down his town of origin of his parents who may not even be Italian.

Try the Archivio di Stato 'patrimonio'

There are no digitized records for this town for your time period. You will need to write to the town and probably the parish.

These records are not on line although you could check italianparishrecords.org. Failing that you will have to identify the parish and write to them.