Those charged with kidnap alone are: Tevita Matangi Fangupo, 23, Becoylee Rogers Paleaaesina, 25, Panepasa Havea, 25 and a woman in her 20s.
Accused of kidnapping and manslaughter are: Masi Vaifale, 34, Seng Lek Liev, 25, Joseph Benjamin Haurua, 33, Aphichart Korhomklang, 30, Sodarith Sao, 25 and Luigi Havea, 26.
In the early stages of the investigation police revealed there were thought to be links to organised crime.
Ms Prutsiriporn had been facing cannabis and methamphetamine charges at the time of her death and friends spoke about her long-running battle with drugs.
A trial date for May next year was set.
Seven of the defendants were remanded in custody, three on bail, to reappear in August.