Im interested in knowing if my ex can move to a different…

The law does not specify a time at which a child can make up their own mind, but as children get older the courts give more weight to their expressed wishes, recognising both that as children reach maturity they are in a better position to decide for themselves, and the practical reality that if teenage children take it upon themselves to refuse contact or otherwise not cooperate with the court's orders, there is little the courts can do to actually force them to comply with either the court or their parents.

If it were the case that all your children were keen to go then I would not recommend you oppose the move absolutely but merely that you ensure reasonable arrangements are in place to maintain contact (i.e. regular skype or telephone access, and holiday arrangements), but based on your assertion that the older child does not want to go and the middle one is conflicted, and that your youngest may not have good reasons for moving (i.e. the idea of staying in a stable may sound fun to a 13 year old child, it may not impress the court as a good reason for the move) then you would seem to have reasonable prospects of resisting the move. There are no guarantees however, as weighing the various pros and cons is a subjective matter which no two judges will necessarily agree upon, and it is certainly beyond the scope of this service, with its limited information about your case, to give firm advice about.

In my view, subject to the above, if the mother is threatening to move in a way that is both disruptive and contrary to your children's interests on its face (i.e. taking them out of school) it may be possible to obtain an interim order from the court preventing her from relocating before you had she have completed the mediation process or even until the court makes a final decision - but you have to apply to the court to secure such an interim order. Once you have such an order in place, nothing changes but if she simply up and moves, you will be in a much better position to seek a recovery order, whereby the court can order the Federal Police to collect your children and bring them home to you.

Naturally any enforcement order for a breach of either an interim order or formal custody arrangements is potentially ugly, messy and expensive, but ultimately it is the final recourse for a wronged parent when one parent is ignoring the other parents rights. By obtaining such an interim order you are simply taking a step toward being able to take such action if necessary. Hopefully, by strengthening your hand in that regard, it will dissuade your ex from risking such action.

I trust my answer assists your understanding but generally you should rely on the recommendations of your own lawyer as they are presumably far more fully briefed as to the circumstances of your case.

Good luck and please rate my answer.

Patrick