Since your grandfather purchased the property by a registered sale deed in the year 1995 and he was in possession and enjoyment of the same ever since purchase and was subsequently enjoyed by his descendants for over 28 years, the claim made by the si called son of original owner is not maintainable at this belated stage.

Besides the possession of this property was very much adverse to him because he had not taken any steps within 12 years of the sale of property, hence you can challenge it properly and get it dismissed.

You can even file a petition under order vii rule 11 cpc to reject the plaint on the same ground stating the plaintiff has no cause of action.

1.death certificates are issued by the respective       Municipal Corporation or Panchayat of the place where the death has occurred. It is issued after due verification of the death. To ascertain its authenticity, you can contact the respective Municipal Corporation or Panchayat and verify the details.

2. File counter-claim in son's suit, challenging death certificate & suit's validity on grounds of limitation. 

3. Provide documentary evidence (e.g. registered will) to dispute death certificate.

4.If you are unable to prove that the death certificate is fraudulent, you may be able to claim adverse possession. Under Article 65 of the Limitation Act, 1963, a person who has held a property for 12 years without the title can claim ownership of the property. In this case, since your grandfather held the title for 10 years, your father held the title for 10 years, and you have held the title for 8 years, you may be able to claim adverse possession.

You need to contest that suit on merits and support the fact that will was not fraudulent.you can also claim the total consideration paid from the said person along with interest 

Take the plea that death certificate is fake 

will is registered and testator appear before registrar office for registration purposes .

will was attested by 2 witnesses 

further what were legal heirs doing for last 42 years 

Hi 

It appears that the son of Person A and B is challenging the WILL itself by relying upon the death certificate. 

you can always ask for the tashildar to submit relevant records and also cross examine him (it is highly impossible to enter the date of death of person after 6 months of his demise).

Now, your defence should be that a) You are in possession by virtue of sale deed executed by Person A in 1995.

Also, law of limitation will be of help to you as the silence of Son of Person A and B from 1995 to 2023  (for 27 years ) cannot be explained to court 

Also, the contents of plaint in OS needs to be carefully studied prior to invoking adverse possession because, when you have a valid title, raising an adverse possession plea can at sometimes be disadvantageous to you. so a careful study of plaint is required. 

There are two procedures for obtaining death certificate.

1. After demise of person, intimation of death is given to MUNICIPAL Authority by legal heir and a death certificate will be issued.
2. If intimation to municipal authority is delayed, legal heir has to submit an application to Tahsildar/EM with affidavit and all. A direction will be given by Tahsildar to municipal authority and death certificate will issued by municipal authority on such direction.

If death certificate  is issued  under 2nd procedure, challenge that the application and affidavit is false.

His claim is also barred by limitation, as limitation for recovering immovable property  is 12 years.

In this case claim of adverse possession will not stand.

- As per law, the limitation to file a case to challenge the Will is 12 years from the date of death of the testator.

- If the person A  has died in 1980 ,  then this Will can be declared as null and void on the ground of date of registration. 

- Hence, you should enquire about his actual date of death for dismissing their cases., and to lodge an FIR against them. 

- Further, if that agriculture land is continuously in use and occupation of you since 1981 , and you having evidences that you was using that land being the owner of the land, then you can be declared as owner of the property after filing a declaration suit before the court on the ground of adverse possession.  

In the given scenario, the person who claims that the will is fraudulent has to prove that Person B died in 1980 and not in 1981. If he succeeds in proving it, then the will becomes invalid and the property devolves upon the legal heirs of Person B as per the laws of inheritance. However, the fact that he has produced a death certificate dated 1980 raises suspicion, as the will was executed in 1981, and it is not clear why this certificate was not produced earlier.

To counter the claim of the person who has filed the suit, you may try to obtain evidence that shows that Person B died in 1981 and not in 1980. This may include hospital records, medical certificates, or affidavits of witnesses who were present at the time of death. You may also try to cross-examine the witnesses who are being produced by the other party to prove the death in 1980.

If you are unable to prove that the new death certificate is not correct, you may try to explore other legal options to protect your property. One such option is to claim adverse possession of the property. However, to claim adverse possession, you need to prove that you have been in possession of the property for a continuous period of 12 years or more, and that possession has been open, peaceful, and without any interruption. In your case, you may be able to claim adverse possession as you have been in possession of the property for a period of 28 years. However, adverse possession claims can be complicated and are subject to legal challenges, so it is advisable to consult a lawyer who specializes in property law before pursuing this option.

In conclusion, to protect your property, you should gather all the relevant evidence to prove that the will is valid and that Person B died in 1981. You may also consider claiming adverse possession if you are unable to prove the validity of the will. However, it is important to seek legal advice before taking any legal action.