Hi, both 2nd party and 3rd party has to register their respective shares getting through the Compromise Decree and once it has registered the Compromise Decree, then 3rd party can sell his share and you can purchase the same.

1. A Release Deed can be executed by the 3rd party in favour of the 2nd party, relinquishing his 25% share.

2. A Public Notice to be published in both vernacular and English newspapers, to rule out anyone from claiming a right in the property. This has to be done before 2nd party makes payment to 3rd party.

Sale deed to third party cannot be cancelled in view of compromise decree wherein third party has 25 per cent share in property 

2) register the compromise decree 

3) third party can then execute sale deed for his 25 per cent share in property to you 

4) stamp duty and registration charges have to be paid 

There is a compromise decree by the court allocating proportionate share of property between both the parties, however even after the judgment both the parties have not taken steps to divide the property as per the court judgment.

in this context either both the parties can draw a partition deed on the basis of the court decree, get the deed registered or file an execution petition to execute the judgment as per the directions of the court, subsequent to which the same can be registered as per court direction. In that event there may not be a necessity for cancelling the registered sale deed now standing on the name of 3rd party. 

For registration, the parties have to pay the stamp duty once again. 

1) once settlement is arrived at between the parties and decree is passed it is binding upon parties 

2) it is doubtful that court would set aside compromise decree

3) you are at liberty to make application to court for setting aside compromise decree if you so desire

Your suggestion is not possible neither any such petition would be entertained by court at this stage. 

It was a compromise decree which cannot be even appealed before an appellate court. 

You may be having different ideas and thoughts arising at different times,  but they cannot be enforced through law. 

1. If it's possible to get hold of the first party and convince him to agree for cancellation of the sale deed, which the first party had executed in favour of 3rd party, by executing a registered Cancellation Deed now.

2. By exercising this option, the problem can be resolved.

Dear Sir/Ma'am,

Since, the bifurcation of the property has not been registered in the documents or with the sub registrar, I shall suggest you to go through the following procedures for the registration of your share of the land. 

Without registration, a buyer has no legal right over the property so, one cannot sell it to anyone under the Transfer of Property Rights Act. Section 17 of the Registration Act, 1908, mandates that documents of immovable property need to be compulsorily registered. Therefore, it is suggested to go through the procedure mentioned below.

Procedure of Registration

• The property documents that need to be registered, should be submitted to the office of the Sub-Registrar of Assurances within whose jurisdiction the property, which is the subject matter of transfer, is situated. The authorised signatories for the seller and the purchaser, have to be present along with two witnesses, for registration of the documents.
• The signatories should carry their proof of identity. The documents that are accepted for this purpose, include Aadhaar Card, PAN Card, or any other proof of identity issued by a government authority. The signatories also have to furnish the power of authority, if they are representing someone else.  
• You need to present the property card to the sub-registrar, along with the original documents and proof of payment of stamp duty. Before registering the documents, the sub-registrar will verify whether adequate stamp duty has been paid for the property, as per the stamp duty ready reckoner. In case there is any deficit in the stamp duty, the registrar will refuse to register the documents.
• Note here that witnesses are quite important in the overall process. The two witnesses that you intend to present during the registration, will also have to establish their identity in front of the sub-registrar. For this purpose, they should also carry their ID proofs and their address proofs. Additionally, their biometric identity will also be scanned during the process.

Execution

Execution is the enforcement of a decree by a judicial process which enables the decree-holder to realize the fruits of the decree and judgment passed by the competent Court in his favour. The Registration Act and Transfer of property Act deals with the manner in which the title in the property can be transferred. An important aspect of execution of a document is attestation of the document. Similarly, section 17 of Registration Act provides the list of documents which require compulsory registration. 

Execution of Sale deeds

• Execution of the sale deed is technically the concluding part of property-purchase process. After a buyer and a seller reach an agreement, they first execute an agreement to sell, a document that sets the terms and conditions based on which the future transaction will take place. A sale deed, also referred to as conveyance deed, is the main document in a transaction of sale and purchase of property. A sale deed acts as the main legal document that evidences the sale and transfer of ownership of property in favour of the buyer from the seller. It also acts as the main document for further sale by the buyer as it establishes his proof of ownership of the property.
• Through the sale deed, the transferor transfers his rights to the transferee. The transferee or the purchaser then acquires absolute ownership of the property. A sale deed is executed after the execution of the agreement to sell, and after compliance of various terms and conditions detailed in the agreement to sell as agreed upon between the buyer and seller. 
  
  

Order XXIII Rule 3 CPC pertaining to the compromise of the suit:

"Compromise of suit: Where it is proved to the satisfaction of the court that a suit has been adjusted wholly or in part by any lawful agreement or compromise, in writing and signed by the parties or where the defendant satisfies the plaintiff in respect of the whole or any part of the subject-matter of the suit, the Court shall order such agreement, compromise or satisfaction to be recorded and shall pass a decree in accordance therewith so far as it relates to the parties to the suit, whether or not "the subject-matter of the agreement, compromise or satisfaction is the same as the subject matter of the suit."

Since, the compromise decree between the 2nd and the 3rd party had been cancelled by the court, this means that the sale deed between 1st and 3rd party and the bifurcation of the property is again a matter of dispute. In this case, whether the sale deed is executed or not, to avoid any risk, registration of land is mandatory before any such sale.