has moved to NZ she has been asked by here old work to make payments towards her Chinese retirement until she is 50.
By under what law? I'm unaware of any country that forces NON-resident people to pay into a pension (especially one that is gov't).
I am wondering if she should make the payments towards her Chinese retirement.
NO
Is she able to receive retirement money from China while she works in NZ?
YES - but it will be taxed in NZ (regardless if the $ is brought back to NZ or not)
Can she receive retirement money from China until she is old enough to retire in NZ and then switch to NZ retirement if it is more?
Yes providing China gov't pays pension to overseas non-residents? There may be a huge concession (a big cut in pension) to those that reside overseas if they expect to get their paid pension in China
When she is old enough to retire in NZ can she receive retirement money from both China and NZ?
Generally no but it's a question from the China pension point of view. If it's a private pension then yes.