"So, hopefully people will come and have a good time for a good cause."
Also featuring in the lineup are covers band Louis and the Curls and young rockers Front Back and Sides, whose members were Tahlia's classmates at Wairarapa College.
Louis and the Curls frontman Louis Murphy-Harris appeared opposite Tahlia in WaiCol's production of Bugsy Malone, and Front Back and Sides represented WaiCol in the 2013 Smokefree Rockquest, coming second in the regional finals.
Rounding up the lineup are acoustic folk duo This Little Orchestra, one of whose members is WaiCol French teacher Jo Brunskill.
Ms Griffis said she is thrilled with the support of the musicians and Tahlia's school chums.
"Lots of wonderful people are donating their talents," she said. "Some of these guys have been out of town for university - and they're coming back to Masterton just to play for Tahlia.
"It should be a pumping night - lots of fun for the young, and young at heart."
Tahlia herself, a talented singer, will also be performing "a number or two", accompanied by Front Back and Sides guitarist Eddie Kerr.
In South Africa, Tahlia will be based in a small village in the Kwazulu-Natal region, where she will be working with children at an orphanage, helping build playground equipment, assisting local farmers and volunteering at a rehabilitation centre for big cats.
She is studying towards a Bachelor of Music at Victoria University, and hopes to work as a composer for films and video games.
Tahlia's fundraising gig is at King Street Live on July 5. Entry is $10. Doors open at 7.30pm.