Your Will may be challenged if in the terms of the will adequate provision is not made from the estate for the proper maintenance and support of the your spouse, child or dependant, the court may, in its discretion, on application by or on behalf of your spouse, child or dependant, order that such provision as the court thinks fit shall be made out of the your estate for the spouse, child or dependant.

In other words if the court does not think you have left enough money to your dependents (spouse or kids) they may order your executors to give them more.

Unfortunately there is no way to prevent people from challenging your Will in an Australian court.

Assuming your Will has been signed and witnessed correctly (as per the instructions that we supply with it), then the challenges are likely to relate to being "fair".

Perhaps you have a son or daughter who you feel does not deserve their "share" of your estate. They may try to challenge the split in court.

Of course you're not going to be there to argue your point, but you can include a statement with your Will where you explain exactly why that person deserves to miss out. This would be a separate document which you sign and date. Keep it factual and not too bitter and twisted.