Saunders, who has written the show based on the music of the girl band, has confirmed all five members - Victoria Beckham, Emma Bunton, Geri Halliwell, Mel C and Mel B - will be present when it launches at the end of the year, reported Contactmusic.
"I am really looking forward to the first night which should happen by the end of the year. All of the Spice Girls should be there. It is called 'Viva Forever' and follows the fortunes of four members of a band with songs by the Spice Girls. But it is not about the Spice Girls any more than 'Mamma Mia!' was about Abba," Saunders said.
The English comedienne previously said the musical made the Spice Girls "emotional".
"During one read through I played one song and then Emma said 'Oh I think I am going to cry I loved this song'. It is a collection of their best memories and they had such a ball, such a great time together," Saunders said.
"Going back and playing all the songs and everything was quite emotional really. Their absolute joy and love of the music and those days is just so palpable," she added.
