It comes a week after police announced 12 people had been charged with the murder of the 20-year-old.
Fox died in Rotorua Hospital of critical injuries on July 28.
Detective Inspector Craig Rawlinson said the further four people faced charges of attempting to pervert the course of justice.
They would appear in Tauranga District Court via audio-visual link on Tuesday and Wednesday.
Those charged were an 18-year-old, a 29-year-old, a 45-year-old and a 62-year-old.
Rawlinson said the investigation into Fox's death was ongoing and police still wanted anyone with information to come forward.
They could contact police via 105, referencing file number 250726/5566.
Alternatively, information could be passed anonymously to Crime Stoppers on 0800 555 111.
