When most people hear the name Knipfing, they immediately think of Kevin James, the beloved comedian known for his role as Doug Heffernan on The King of Queens, or his brother Gary Valentine, who has also made a name for himself in comedy. But there is another member of this talented family whose story is equally compelling, even though she has deliberately chosen to stay out of the spotlight. Leslie Knipfing is the younger sister of Kevin James and Gary Valentine. While her brothers built careers in front of the camera, Leslie built her life around something else entirely: helping others,…