Land sold without our consent advice needed

if she sold the land without their respective permission is wrong and  crime. you can initiate appropriate action  by the support of all records with local lawyer's advice and act at your earliest

If any other brother sells the joint property without the consent of the other brother, then for this, make a civil suit for partition and in that suit, make an application order 39 Rule 1.2 CPC to the effect that the suit will be held for the period of trial. Not sold

Serve a legal notice to the broker and if possible plant a notice board over the property for making aware the public about the names of the owners! Aside file an injunction suit and file a FIR against your sister-in-law  and the broker.

Unless the inherited property is divided in metes and bounds between co-sharers and each co-sharer gets his share with such boundaries, the presumption is that the property is joint.  The land records during Nizam time was not maintained like in British India, and there were flaws in Dharani portal site.  In a village to sell the joint property by a single co-sharer's wife, when her husband is suffering from an unsound mind is difficult to my knowledge, unless the sale is collusive in nature.  Do not delay the issue, once it came to your knowledge, contact a local advocate and proceed legally for further remedy.

Has the sale been completed through a registered sale deed? If so, who has executed the conveyance?  as already suggested, you may file a partition deed.

Your sister in law cannot sell the property by herself even though the patta passbook is on her husband's name. 

You say that this property is on the joint names of all the siblings, in that case the patta passbook alone cannot be sufficient for the buyer to verify the property documents, he should have verified the original  registered property documents, however if the property was sold by an unregistered document then the sale of property is invalid and illegal.

If she had sold the property by fraudulent manner, you may first file a suit for partition and an application for injunction  restraining your brother from alienating or  encumbering the property in any manner and may mention that the current sale of property is not binding on you. 

You have to approach court with an emergent suit to file the same in the vacation court if the courts are on vacation now or closed due to lock down.

Contact a local advocate and proceed as suggested. 

I agree with the experts opinion and advise.

Your sister-in-law has no authority to sell the land without written permission of all four brothers, if she has sold, she has committed cheating and fraud for that she has to be booked, prosecuted and punished.

Besides this all of you (or either of you) should file a suit for cancellation of sale deed(s),  declaration, rendition of accounts, mesne profits, permanent and mandatory injunction in the court of jurisdiction.

It is better to consult and engage a local prudent lawyer for analysing facts / documents, professional advise and necessary proceeding.