"Life is short, and it's there to be lived. I'm so pleased Jarrah lived it to the full, and in a way that gave back to society, not in a frivolous way," Harris told the ABC.
Young's brother Joel was also on the tour bus but survived the crash.
Tributes have also been paid to Penberthy, who was originally from Inverell, in northern New South Wales.
"So Sad. You took life with 2 hands and gave it hell. RIP Sarie," one person wrote on Facebook.
Another added: "You were the perfect partner in crime and a fantastic friend. The memories I have are the kind that last a lifetime."
The crash occurred when a wheel fell off the bus, the Seven Network reported yesterday.
An Australian Department of Foreign Affairs and Trade spokeswoman said 12 people were in the bus when it crashed.
A senior consular official from the Australian High Commission in Pretoria has travelled to the site to assist the Australians and to liaise with local authorities.
The department is also providing consular assistance to the families in Australia.
