Wearing white party T-shirts, some managed to get seats in the packed courtroom while others waited outside.
Two African National Congress Women’s League members in their green and black attire were also among the early arrivals at the court.
Security guards manned both doors of the court as the group outside swelled to around 50.
Two-year-old Yonelisa Mali and her three-year-old cousin Zandile Mali were found dead in a toilet cubicle last Tuesday.
Four men appeared in court on Friday on charges of rape, murder and kidnapping. The case was postponed for them to apply for Legal Aid.
On Monday, a fifth man, aged 29, appeared in court. He was arrested in Alexandra, north of Johannesburg, on Friday after being on the run.
After the bodies of the children were discovered, angry Diepsloot residents stoned cars and burnt tyres in the street outside the local police station in protest.