Christa C. Cottrell’s law practice was already complicated before her twin daughters arrived on the scene, just before she was set to go to trial in February 2014.It was a trial five years in the making. But Cottrell’s colleagues at Kirkland & Ellis LLP were supportive of her and her family — Cottrell gave birth to a third baby girl 14 months later, and in both instances, she was able to take a full leave with both pregnancies.The 39-year-old equity partner handles complex commercial and antitrust …