Complex sentence: Bleeker briefly moved to Philadelphia while the others continued developing the band, and when Bleeker asked to rejoin, he took up the bass so that Courtney could play guitar, making it easier for him to sing.
Split into simpler sentences: Bleeker briefly moved to Philadelphia while the others continued developing the band. When Bleeker asked to rejoin, he took up the bass so that Courtney could play guitar, making it easier for him to sing.