Who is Kirsten Greene from Just Listen and what is their importance?

Kirsten Greene is Annabel's sister. She got her first modeling job at the age of eight. She is described as bubbly and able to communicate with little more than a look. Kirsten is the first to notice that Whitney is in distress both emotionally and physically, and she tries to bring it to the attention of the rest of the family. Whitney, however, manages to convince them that all is well.

Kirsten is the first to leave the nest, going to New York to pursue a modeling career which she gives up not too long afterward. Instead, she returns to school where she discovers an affinity for film. An instructor teaches her the art of communication, and Kirsten surprises her family by learning how to listen as well as she knows how to talk.