What is the legal procedure to contest a will’s validity in court?

livemint.com:

—Name withheld on request We assume that the deceased, your uncle, was a Hindu and that he was survived by his wife and son. However, in your Uncle’s will, we understand that he has bequeathed all his estate/ properties to the charities thereby not giving any bequest to the legitimate heirs of your uncle. You may note that there is no embargo or restrictions under the Hindu Succession Act for bequeathing the entire estate for charitable purposes.

Therefore, unless and until the son and his spouse are able to prove before the court that the will was made by fraud or coercion, the disposition/ bequest made under the will cannot be disregarded by the court.   —Name withheld on request A will can be validly made by any adult of sound mind. The testamentary or dispositive capacity must be proved to the satisfaction of the court.

Further, the will must be made of the testator’s volition, absent of fraud, coercion, undue influence or other factors that take away the testator’s free agency.  There is no form, but its execution must be attested by at least two witnesses at the direction of the testator; each witness must attest the will in the presence of the testator, though both need not be present at the same time. Proof of a will means its proof in its solemn form. Such proof can only be established by complying with all these requirements and adducing evidence to prove it.