Who is Jenny from Nothing Can Keep Us Together: A Gossip Girl Novel and what is their importance?

Jenny is Dan's younger sister. She has to leave her current school after a series of scandals. She has a hard time finding another appropriate school, but is finally accepted by Waverly Prep, where she can focus on her art. More of a "wannabe" than the other characters, Jenny idealizes Serena. She also makes out with Nate at the end of the book.