Undue influence

If a person is coerced into making a will, it can be deemed invalid.

Evidence

There is a heavy burden of proof and it would need to be clearly evidenced that this kind of coercion took place, which is very difficult to pore. Simply persuading someone to change their will is not enough –they have to have been forced or frightened into doing so.

Fraudulent calumny

Fraudulent calumny is an even higher standard of proof and it has to be evidenced that the person who made the will had their mind poisoned by the perpetrator to such an extent they changed their will.