Ask her to get an international driver's licence from New Zealand. She can use it in most any country except New Zealand and it is issued/valid for a year (usually). I'm not sure what the policy is for adding her on you insurance policy, you'll have to ask your insurance company but if you are renting a car, it's a lot easier and cheaper to get the rental company insurance coverage to cover her. Like any policy, remember to read the fine print and make sure you get the adequate coverage.