ADR, sometimes known as Automatic Dailogue Replacement or Additional Dialogue Recording, is when the actor goes into a sound studio to revoice any dialogue that may be hard to hear on the film, or may not sound just right. A studio engineer works with the actor in front of a video of their scene and the voice is rerecorded then and there.
The ADR for The Tree took place in Sydney, Perth and Brisbane, to fit in with the actor's work and living locations. For the young child actors, it was their first experience of what can be a very strange activity. But they took to it like ducks to water. It was also a great opportunity to catch up again.