Complex sentence: Towards the end of 2009, Callista began working with renowned producer Stephen Short (Augustana, Camera Can't Lie) with whom they immediately started the process of writing and developing new songs in pursuit of a professional career in the music industry.
Split into simpler sentences: Towards the end of 2009, Callista began working with renowned producer Stephen Short (Augustana, Camera Can't Lie). They immediately started the process of writing and developing new songs in pursuit of a professional career in the music industry.