Why did the theater manager want Carlotta to sing in the Phantom of the Opera?

The theater manager wanted Carlotta to sing in "The Phantom of the Opera" because she was the star soprano of the Opera house, and her performances were essential for attracting audiences and ensuring the theater's success. However, this decision was complicated by the mysterious presence of the Phantom, who favored Christine Daaé and sought to manipulate events to place her in the spotlight instead. The tension between Carlotta's established status and the Phantom's obsession with Christine drives much of the conflict in the story.