You can file a FIR for cheating. You can also file civil suit for declaration of title.

1. It is not clear what is the basis of their claim over your land.

2. if indeed your grand father sold this land to Party 1 which by making rounds came to the hands of P3 then he has every right to restrict your entry into the land.

3. if this is not so then you can file a suit for declaration and for injunction.

Your grandfather should file suit to set aside fraudulent transfer of land 

2) take plea that he was cheated by party 1 

3) that he was illiterate and not aware of contents of agreement signed by him . Fraud was discovered recently and suit was filed within period of 3 years of discovery of fraud 

4) he should seek injunction restraining sale of property by by party 3 

The Transfer of Property will be regulated through the first sale deed even if your grandfather was illiterate it was his responsibility to know that what he is transferring in this case you have very limited chances even if you go to the court and it will be taking lot of time to prove that he has sold only small portion of the plot as the registration of the  property was done for 90% of area

It would be better for you to take proper legal guidelines by showing complete files of your case to an advocate so that you can take a right path to handle your issues

Hello,

it will be very difficult to get back the land now since the party one has passed away. 

Still the legal heirs can file the suit and say that the sale deed are fraud and may challenge all the subsequent sale deed. 

Is there any prove of the consideration that was paid to your grand father as against the original sale? 

Regards 

1. How would you prove the act of cheating? Did your grandfather execute the sale deed personally in favour of party 1 or it was done through an agent by executing a Power of Attorney?

2. You have the remedy of filing a suit for declaration to declare the sale deed in favour of Party 1 and all subsequently executed sale deeds as illegal but you will have to prove the fraudulent act of the buyer. 

See the owner that is grand father or legal heirs of grand father need to file a suit for cancellation of sale made to party 1 and subsequent sells there of on ground that sale to first party was done by fraud and cheating same need to be established before the court and further you need to seek possession of the property in the suit

1. File proper grievance petition before the local district collector, with all the facts and documentary evidences, and pray for proper hearing and restoration of land, on grounds of fraud, intimidation and cheating.

2. ALSO check whether you land was a "new tenure (navi sharte)" land and whether you are covered under ST /SC /OBC category. This will help you in your case, IF you show that you have no land for self-sustenance of family.

Keep Smiling .... Hemant Agarwal

You have a very weak case, if he (party3) has papers of ownership of land then you can't stop him doing anything. you can go for set-aside the transfer deed (grandfather to party1) but no chances for success as per the available facts.

SORRY

Dear Sir,

You have to file suit for possession and declaration and produce all available evidence and get decree from Civil court.

Whether the property in dispute is in your possession and enjoyment from the beginning?

If so you may file a suit for declaration of title on the basis of possession and enjoyment by producing documentary evidences to prove this.

Even though your claim may not be maintainable since it will be barred by limitation to claim cheating of the first buyer, try costs nothing.