Dearest reader,
I have gone through your query and I would like to answer the same.
As you have mentioned the couple has proof that they did not do the theft then there is not a single piece of sense in the allegations made by the sister-in-law as they were just baseless and will be considered as public humiliations.
The couple can file a complaint against the sister-in-law for the act of public criminal defamation under Section 499 of the Indian Penal Code. They can also refer to Section 500 of IPC as this provision tends to penalize anyone who is found guilty of defamation. From my point of view, they will surely win the case as in the case of Subramanian Swamy v. Union of India (2016), the Supreme Court has already upheld the constitutionality of criminal defamation in view of protecting the reputation of individuals.
If the couple doesn’t want they can file the defamation complaint directly against the sister-in-law without involving the other family members.
Now let’s come to the topic of disownment. Since the father has only verbally disowned the couple, let me make this clear that disowning the child from the father’s property cannot be done verbally or without due legal process.
If the property is self-acquired by the father, then as per the provisions of the Hindu Succession Act, of 1956, he has the right to disown the son but only by following a proper legal procedure. But If the property is ancestral, then the couple has a legal right to the property and the disownment words of the father are holding no weight. This can be seen in the case of M. Yogendra & Ors. v. Leelamma N. & Ors. (2009) as the Supreme Court has held that rights in the ancestral property are inherent and can’t be taken away without any due process of law.
At last, I would suggest the couple file a complaint in the nearest police station about the criminal defamation they have suffered by their sister-in-law. Additionally, the disownment by the father holds no significance unless formalized by following a due process of law.
