MIAMI — The 29-year-old Mexican farmworker was stressed and afraid. Her husband had just been detained by immigration authorities as he left a South Florida construction site and was about to be deported. She feared the same would soon happen to her. What would become of her two kids? So she called Nora Sandigo, an immigration activist who has accepted responsibility for 1,250 children, becoming an essential part of emergency planning for people who are in the U.S.