Having already charged one man late last year, police charged another alleged offender last month, accusing him of punching the host after an argument over the music on September 5, 2014.
The party was held for the victim’s sister’s birthday.
The 18-year-old suffered a bruised eye, swollen face and chipped teeth.
The latest person of interest (17) was charged with assault occasioning bodily harm.
He is due to face Joondalup Children’s Court on March 18.