From 1 November 2021 parents will be considered to be an “immediate family member”
You can travel to Australia if you are an immediate family member of:
an Australian citizen
an Australian permanent resident (permanent visa holder)
a New Zealand citizen who is usually resident in Australia.
https://covid19.homeaffairs.gov.au/immediate-family-australian-citizens-or-permanent-residents-or-new-zealand-citizens-usually-resident-australia