| Unless your sister lives in a very windy area then the main thing will be to see that the current staking doesn't get in the way of new stem growth. Once the tree is well-rooted then it will probably be wind resistant. (Exception - high wind after sustained torrential rain has made the soil fluid.) If she's growing the tree for juvenile foliage then she may need to take off the top couple of metres to initiate the growth of new stems from further down. As an ongoing management process the tips probably need to be taken back to stop any of them 'deciding' to become the new leader. I'm not sure about E gunnii, but in other eucs that have produced new stems from the lignotuber - the stems take a few years to become firmly attached. They seem to be willing to part company with the trunk at the merest hint of a bump. Management is similar to what you would use if you were growing a Cornus or Salix for coloured winter stems. | 
