Complex sentence: Christie added to his earlier success by winning the February 2015-SPFL Young Player of the Month award, and his eye-catching form over the whole season subsequently saw him shortlisted for the Young Player of the Year award.
Split into simpler sentences: Christie added to his earlier success by winning the February 2015-SPFL Young Player of the Month award. His eye-catching form over the season saw him shortlisted for the Young Player of the Year award.