Obtaining Dual Citizenship
I acquired Italian citizenship for my wife and three sons. It's not easy, but worth it in the end. As mentioned, there are websites dedicated to helping you through the process, and they will make it much easier. I wouldnt try without one. Don't remember which I used. We could not get my grandfathers birth certificate from his small southern town. Eventually, I had to send my son over there to get it. Letters, and emails, and phone calls don't really motivate them. Then I had to get the marriage certificate of my grandparents. Fortunately it was in NYC, but the church had long ago been torn down.
They have records of everything in NYC, but not of their marriage. Seems on Ellis Island they misspelled his name, so identities never quite matched.
Finally, we had everything needed. We went to The consulate in NYC. They basically screamed at us, told us we could never become citizens despite having the documents, and they basically through us out.
So, we went to the Consulate in Houston, and it was completely different. We were welcomed. They gave us some minor forms to fill out. We gave them pictures. Couldn't have taken more than an hour for all of us to get the citizenship. Italian passports arrived a few weeks later.
Overall, unless you have unlimited time and patience, I would work with a company to assist you in this. Good luck.