Dolores Clara Fernández Huerta is an American labor leader and civil rights activist who, with Cesar Chavez, is a co-founder of the National Farmworkers Association, which later became the United Farm Workers.
She would have been ~16 when the trio met her in 1946, and at the time would have only been named Dolores Clara Fernandez (she is the daughter of Juan Fernández and Alicia Chávez) because she did not marry her first husband Ralph Head (with whom she had five children) until college, and her 2nd husband Ventura Huerta (with whom she had two) until after that.
After the divorce from her 2nd husband (whose surname Dolores kept) she had an unmarried romance (and four more children) with Richard Chavez, the brother of Cesar Chavez. This made them similar to siblings-in-law, though not technically, since there was no marriage between Richard and Dolores.
In real life, Dolores was a baton-twirler ("majorette") for a team at Stockton High School, as well as being a member of the Girl Scouts. It's not clear if this team was a component of a marching band though.