These are two separate but often linked ways of challenging a will. Fraud involves dishonesty. It is judged in the light of what a person knew at the time but the standard of what constitutes honest conduct is judged objectively rather than according to the standards of each individual. If a person knowingly appropriates another person’s property they will be found dishonest & the challenge to the Will will be successful, even if they honestly see nothing wrong with such behaviour.
Dishonest misrepresentations made to the testator are the most common form of probate fraud inducing a testator to make a gift to someone he would not otherwise do, or revoke one he would not otherwise have revoked.
Another typical case is where someone a testator does not know prepares a will in their own favour. Such persons are under an onus to remove the suspicion that the testator did not know and approve the will to be made.
Challenging a Will through an allegation of forgery usually will require expert hand writing evidence. The standard of proof is high.