Will vasiyat

A.Dear Sir,
Without going through full details how relevant judgements can be traced out.
Section 61 in The Indian Succession Act, 1925
61 Will obtained by fraud, coercion or importunity. —A Will or any part of a Will, the making of which has been caused by fraud or coercion, or by such importunity as takes away the free agency of the testator, is void. Illustrations
(i) A, falsely and knowingly, represents to the testator, that the testator's only child is dead, or that he has done some undutiful act and thereby induces the testator to make a will in his, A's favour; such Will has been obtained by fraud, and is invalid.
(ii) A, by fraud and deception, prevails upon the testator to bequeath a legacy to him. The bequest is void.
(iii) A, being a prisoner by lawful authority, makes his Will. The Will is not invalid by reason of the imprisonment.
(iv) A, threatens to shoot B, or to burn his house or to cause him to be arrested on a criminal charge, unless he makes a bequest in favour of C. B, in consequence, makes a bequest in favour of C. The bequest is void, the making of it having been caused by coercion.
(v) A, being of sufficient intellect, if undisturbed by the influence of others, to make a Will yet being so much under the control of B that he is not a free agent, makes a Will dictated by B. It appears that he would not have executed the Will but for fear of B. The Will is invalid.