To quote the NZIS:
You donít need a visa or permit if youíre:
an Australian citizen, or Australian resident who holds a current Australian Resident Return Visa
So provided Sarah holds a current Australian Resident Return Visa - she is entitled to this as a legal migrant to Australia - she is entitled to live and work in New Zealand too.
Of course, Sarah, it would be wise to check for how long the Resident Return Visa in your passport will remain valid. If it runs out and you don't yet have NZ citizenship or an entitlement to remain here by virtue of arranging a work permit, you might have a problem. So I'd check up on how long your ARRV will remain valid. :smile