Complex sentence: From the 2014--15 season, HNK Hajduk Split Reserves (or Hajduk II) was formed and replaced the U- 19 team to compete in Croatia's reorganised Third Division.
Split into simpler sentences: From the 2014--15 season, HNK Hajduk Split Reserves (or Hajduk II) was formed and replaced the U- 19 team. The reserve team will compete in Croatia's reorganised Third Division.