In South Australia, for a will to be legal it must be
- in writing
- signed by the testator in the presence of two or more witnesses
- appear as though the testator intended to give effect to it by signing it
- signed by the witnesses who sign their names as witnesses to the will in the presence of the testator
If a will is not as per the above, the estate may be dealt with as if there were no will unless a court orders otherwise. Except for some cases where you are a sailor lost at sea or a member of the defence forces.
A court may still consider a will to be valid if its not witnessed property if they are satisfied the document expresses the testamentary intentions of the deceased, and can admit the document to probate. An application needs to be made to the court and can be quite expensive.