Mia and Charlie Martin, and Jazmine and Zac McCulloch are among more than 200 rising stars chosen for the Australian Performing Arts Network-produced show at Perth Concert Hall.
APAN artistic director Marina Del Basso said more than 400 song and dance hopefuls from 57 WA performing arts schools auditioned.
Young performers will support Perth-born McKenney in hits from such shows as The Boy from Oz, Guys and Dolls, Legally Blond, The Lion King, and Mamma Mia.
Part proceeds from shows at 2pm and 6pm will go to Telethon. Tickets are available from Ticketek.