Complex sentence: Fred Langone also said in his book that his grandfather was from Potenza, although he didn't say which grandfather, but his maternal grandfather, Luigi Poto, was from Castelcivita.
Split into simpler sentences: Fred Langone also said in his book that his grandfather was from Potenza. He didn't say which grandfather, but his maternal grandfather, Luigi Poto, was from Castelcivita.