I should add... You need a lawyer if you need to amend docs due to misspellings or errors in ancestors birth/marriage/death docs.
We had to throw away a perfect line because MILs birth certificate was a cluster you-know-what of misspellings and errors. But I'd gotten her parents docs from Sicily, found her parent's naturalization docs first, it was a clean line except for her birth cert. She'd been born at home (not uncommon in the 1920's) and they'd registered the birth after the fact. Her mother (husbands grandmother) had very poor english and had just given birth, so I'm not surprised the errors weren't caught.. MIL's fathers last name (and therefore her last name) was misspelled. Her mother's first name and maiden name were both misspelled. MIL's first name was a variation of the name she used for every official document later. - including her passport, marriage certificate, etc. (That last would have probably been ok, but not the rest.) It would have required a lawyer to amend the birth certificate to correct it all. And some jurisdictions don't let you do it.
The upshot of the process, for Italy, is:
- get birth certs from latest anscestor from Italy. Different comune have different methods. When I did it, it was send a letter with a self addressed envelope and 10 euro in cash to cover postage with your request for an official, long form, international, birth and/or marriage certificate.
- request a search for documents from NARA to get the c-file number of the naturalization docs.
- request your own birth/marriage certificates.
- request your parent's birth/marriage/divorce/death certificates. All marriages, all divorces (if any). You need the parent that isn't part of your line.
- rinse and repeat for any grandparents that are in your line going back to the last ancestor in italy (the one you are claiming through).
Then you wait.... and wait... and wait....
After 2 months, resend requests to italy. Modify the request to broaden potential birth dates. Consider adjacent comune and send requests to them. (One of my husbands grandparents was from the town next door to the town of the other 3. )
(It took me 18 months to get all 4 grandparents docs because paternal grandma fibbed about her age to the family, and maternal grandpa was literally born on the other side of the train tracks as the rest of them.)
When you get your domestic documents - send them off to the secretary of state of the state they were issued to get them apostilled. That's an international notarization sort of.
If you're lucky, you get a NARA response with the c-file number. You take this number and request the naturalization docs from USCIS. (Current wait time is over 200 days. When i was doing it, it was only 2 weeks.)
If you get a NARA nothing found there are steps to request a Certificate of None Existence. (CONE)... I don't remember if this is through NARA (national archives) or USCIS. But if your ancestor didn't naturalize, you need this CONE to show that. I didn't have to do this step.
All of this is the long way of saying - most of the work is just writing letters, putting in online requests, etc. And then waiting. And waiting. And waiting.
You should probably learn how the prenotami system works for getting consulate appointments. Several consulates have serious backlogs and aren't opening appointments... Getting an appointment can take a year of trying online. A lawyer can't help with this. ... and then the appointment is often 2 years out.
OK... too much info, but I'm actively helping the nephew who is in the middle of the process...