Who is Sinita from In the Time of the Butterflies and what is their importance?

Sinita Perozo is a student at Inmaculada Conception, where she is sent after all of her male relatives were killed for opposing Trujillo. Sinita teaches Minerva about Trujillo's crimes, and while the girls are performing before the dictator, she points a bow and arrow. Sinita is stopped by Trujillo's son, Ramfis.