Time bar on disputing joint family agreements

Considerations that support a family arrangement; disputes are avoided in the family, family property is continued in the family , the honor of the family is safeguarded, etc etc

 The said settlement is reduced in writing and signed by all parties and registered?

The said document could be MoU that is reduced in writing to repeat what the parties ( Family) had already had agreed and have been complying with the terms narrated in said document, even before the execution of family deed and its registration is not required. However it does not suffice to create title...........or interest.

Supreme Court of India

Tek Bahadur Bhujil vs Debi Singh Bhujil And Ors.

12. Family arrangement as such can be arrived at orally. Its terms may be recorded in writing as a memorandum of what had been agreed upon between the parties. The memorandum need not be prepared for the purpose of being used as a document on which future title of the parties be founded. It is usually prepared as a record of what had been agreed upon so that there be no hazy notions about it in future. It is only when the parties reduce the family arrangement in writing with the purpose of using that writing as proof of what they had arranged and, where the arrangement is brought about by the document as such, that the document would require registration as it is then that it would be a document of title declaring for future what rights in what properties the parties possess.

https://indiankanoon.org/doc/818453/

You may go thru:

Central Government Act

Section 17 in The Registration Act, 1908

17. Documents of which registration is compulsory.—(l) The following documents shall be registered, if the property to which they relate is situate in a district in which, and if they have been executed on or after the date on which, Act No. XVI of 1864, or the Indian Registration Act, 1866, or the Indian Registration Act, 1871, or the Indian Registration Act, 1877, or this Act came or comes into force, namely:— (b) other non-testamentary instruments which purport or operate to create, declare, assign, limit or extinguish, whether in present or in future, any right, title or interest, whether vested or contingent, of the value of one hundred rupees and upwards, to or in immovable property;

https://indiankanoon.org/doc/561156/

Thus a family settlement that purports to assign immovable property must be mandatorily registered or the deed would be invalid

You may also go thru:

Central Government Act

Section 35 in The Indian Stamp Act, 1899

35. Instruments not duly stamped inadmissible in evidence, etc

https://indiankanoon.org/doc/176042882/

Central Government Act

Section 49 in The Registration Act, 1908

49. Effect of non-registration of documents required to be registered.—

https://indiankanoon.org/doc/1768154/

A family arrangement can remain as binding on the parties who have taken advantage under the agreement from revoking or challenging the same and can operates as an estoppel to preclude the parties involved….

It is felt that, except with a court decree, a duly executed family settlement cannot be revoked

A duly executed family settlement can be challenged in a court of law like any agreement that is striked  by some fraud or coercion, or if there is any misrepresentation of facts regarding the title of the disputed property, and/or if there is improper execution of the agreement.