Complex sentence: Despite the loss of Koppes, however, Arista decided to stand by their contract and back another Church recording session and so, upon finishing their side projects, Kilbey and Willson-Piper began writing new material.
Split into simpler sentences: Despite the loss of Koppes, Arista stood by their contract and backed another recording session. Upon finishing their side projects, Kilbey and Willson-Piper decided to write new material.