Complex sentence: Bidam being the Sangdaedeung will automatically become the next ruler if Queen Seondeok died without naming her heir, however years after she appointed Bidam to his position, she still refused to name her successor.
Split into simpler sentences: Bidam being the Sangdaedeung will automatically become the next ruler if Queen Seondeok died without naming her heir. However, years after she appointed Bidam to his position, she still refused to name her successor.