Complex sentence: Gary Barlow, Kelly Rowland and Tulisa joined the panel in series 8 as replacements for Cowell, Minogue and Cole, though Rowland left before series 9 and was replaced by Nicole Scherzinger.
Split into simpler sentences: Gary Barlow, Kelly Rowland and Tulisa joined the panel in series 8 as replacements for Simon, Dannii, and Cheryl. However, Rowland left before series 9 and was replaced by Nicole Scherzinger.