The mutation in the name of a person can only be done only after obtaining the relinquishment deed from the other legal heirs. Now the DDA must have received the relinquishment deeds and then mutated the property. Moreover, the certified copy of the relinquishment deed must be obtained from the registrar office aong with the registered mutation and other documents.

3 years is the limitation period for challenging the mutation and ownership of the property.

Nobody will now file a suit. 

As a precautionary measure you should take affidavits and register it from the sellers that fhey had given relinquishment deeds.

Assumption and presumption are not legally valid terms in law.

For mutation of properties, just a NOC would be sufficient and there is no necessity for relinquishment deed to be executed by the cosharers of the property.

Without the cosharers executing a registered relinquishment deed in favor of the chosen cosharer, the said cosharer cannot acquire clear and marketable title to the entire property, hence the sale of property by the said person cannot be held valid and it is always disputable because the seller is having  defective title.

The proof of relinquishment is the registered deed.

The flimsy reasons given by the seller or your assumptions on the probabilities could land you in trouble after purchasing the property

Therefore on the basis of the contents of your post, it can be opined that  without  the proof of any relinquishment deed it is not advisable to purchase the property  which is termed to have defective title. 

Yes you can challenge the same. Only limitation may affect you. 

Dont go ahead in purchase of property 

title is not clear and marketable 

you will face problems in selling the property 

legal heir can take the plea that he was not aware of conveyance and discovered fraudulent transfer recently and has filed suit within period of 3 years 

Mutation letter followed with Conveyance deed in favour of the legal heirs are sufficient.   There would be no problem in future since the RD deposited with the DDA is not even registered but is a part of DDA record based on which the mutation had been done.  When the mutation has been done, the RD become redundant.  You are very right that the legal heir cannot challenge the mutation/conveyance deed after 23 years.  However, in case, you have any doubt, and it is challenged, the mutation is not in the sky but in the record of DDA which can be proved with no doubts

As you have rightly said, the legal heirs cannot challenge the mutation/conveyance deed after 23 years. The sellers can very well obtain certified copies of the relinquishment deeds from the registry. To be on the safer side, please engage a lawyer to scrutinize all the documents before going ahead with the purchase.

Dear Client,

                    It is well known that if someone is offering to sell you a property, always require the original of the Certificate of Title before giving them your money.The transfer of property through Relinquishment deed can be for consideration or without consideration or without any exchange of money.The need to create a relinquishment deed typically arises, when a property owner dies intestate, i.e., without a will and the legal heirs decide to give up their right in the said property in favour of a co-owner.Only co-owners of a property can relinquish their share in the property. Also, they can relinquish their share only in favour of another co-owner.The Gujarat High Court, on July 7, 2021, said that a document, under which the right on a property is to be relinquished, requires to be registered under the Registration Act. Unless the document is registered, the document cannot be treated as a relinquishment deed.Hence, you might also conduct your own due diligence against the property and might also visit DLRO office for further information related to the land before buying.

Thanks & Regards