Sometimes there is no paper trail and there never will be. I have oral history (and the name is listed on a death certificate as the father) of who my 3rd ggf's father was. I basically took it with a grain of salt...UNTIL dna testing. I tested my grandmother and two of her siblings, they all match as 4th-5th cousins with several people who descend from the purported 4th ggf's parents. In fact, they have close to a hundred dna matches who are related on this line. So, for me, its pretty well "confirmed".