Why did Alvarez chose to begin her novel by introducing the reader Dede Mirabel and then move back in time?

Write three paragraphs considering why Alvarez might have chosen to begin the novel by introducing the reader to Dede Mirabel and then move back in time. How is the Mirabel family described? How might knowing that three of the sisters will die detract from or add to the novel's narrative arc?

In the time of the butterflies