Julie L. Trester and Corey T. Hickman, attorneys at Cozen O’Connor, don’t specialize in immigration law. But the pair recently won an asylum case for their client — a 21-year-old Mexican woman and three of her four children.Their client arrived with her three children at the U.S.-Mexico border in the summer of 2015. Two months after crossing the border, she traveled to suburban Cook County where some of her relatives lived. Her fourth child was born here.Her case was first taken up by the National …