A 16-year-old boy punched and kicked Laa Chol and held her as she was fatally stabbed at a Melbourne apartment party with the entire attack captured on CCTV cameras, a court has been told.

The boy faced a children's court on Wednesday when prosecutors sought charges of assault and being an accessory after the fact of murder be heard by the Supreme Court, where maximum penalties are significantly tougher.

Laa Chol.

A 17-year-old Sunshine North boy has been charged with Ms Chol's murder at an A'Beckett Street short-stay apartment complex on July 21 this year.

His case will automatically go to the Supreme Court, and prosecutors say holding the two cases together would reduce resources and save Ms Chol's family the trauma of two trials.