Why did Sultana's father marry again? How did Sultana feel about this?

Sultana's father decided to marry again to bring the number of his wives back to four. Father married Randa, a woman Sultana set out to dislike because she was a replacement for her mother but discovered she could not dislike her. Randa was young, only a few years older than Sultana, and frightened. Sultana befriended Randa and allowed her to join a group Sultana had created with two other friends that was supposed to help promote the independence of women.