Complex sentence: Kelly Hogan, an old friend of Leitman's, offered to provide music for the film and soundtrack, and recorded songs with the combo, The Corn Sisters, Carolyn Mark and Neko Case.
Split into simpler sentences: Kelly Hogan, an old friend of Leitman's, offered to provide music for the film and soundtrack. Her band, The Corn Sisters, also included Carolyn Mark and Neko Case.