Grandmother is at liberty to revoke the will and execute fresh will bequeathing property to only one of your sibling 

2) will is required to be attested by 2 witnesses 

3) you are at liberty to challenge the will of there are suspicious circumstances surrounding the will 

Firstly the property which belonged to your grandmother is not ancestral property in nature.

It becomes her own and absolute property.

If the previous Will written by her was cancelled and new Will was written by a registered document, then the latest Will only shall be legally valid instrument.

The beneficiary of the latest Will are the only person/s entitled to acquire the properties bequeathed in the Will, if the other persons were left out by the testator without allotting any share in any property, then it cannot be claimed a s right by the dissatisfied members of the same family because it was the absolute property of the testator and she had full rights to dispose the properties in any manner as per desire and wish.

However if there is a suspicion about any fraud or acts of forgery then the Will can be challenged by the other siblings.

Certain elements, such as, a shaky and doubtful signature, a feeble or uncertain mind of the testator, unfair disposition of property, unjust exclusion of legal heirs, and the active involvement of the major beneficiary in the execution of the will, are indications of suspicious circumstances.

If you have any slightest indications of any of the above mentioned items, you can challenge the Will.  

Subsequent will is suspect will as it was registered in opaque manner without the  knowledge and consent of other legal heirs. It was registered so that it should look  genuine other wise an un registered will is as valid and enforceable as registered will. This will can be challenged on ground coercion and fraud. If executer of the  will is aged person, the  will has to be accompanied by a doctor’s certificate  as the  mental and physical fitness of the  person  at the  time of executing will. It can also be challenged it the  property mentioned in the  will not self earned property of will maker. Coz, will of ancestral property is not executable.

1. You shall have to first find out by scrutinising the Will whether the second will has been  registered by coercion, fraud or any other unlawful way or not.

2. If the property is situated at a place where Probate of the Will is must then the executor of the will shall have to avail probate of the said Will by filing an application for which all the legal heirs including you shall be supplied with copy of the said application for your giving consent or contest the application.

3. At that time you can contest the probate application fittingly challenging the validity of the Will.

1. Challenge the second registered WILL in the jurisdictional competent Court by giving legal ground, that it was executed by your grandmother, under threat, coercion, undue influence by one of your siblings.

2.  Bring Injunction Order from the jurisdictional Court not to create any third party right by way of sale, modification, mortgage or renting of the property.

Yes you can file a suit and get a atay in the said premises

- As per law, the registration of a Will is not mandatory , and it can be written in the presence of at least two witnesses 

- Since, this new WILL is having only one witness , then it is not a valid Will , and it cannot be executed by the process of law. 

- Hence, you can file a probate petition for the probate the last Will before the court, if that sibling is not agree for giving others share in the property . 

- Further, if he wanted to sell the property , then you can file an Injunction petition before the court for restraining him from selling , renting or doing any transaction without getting the consent of all the legal heirs.

A person is legally allowed to change their will as many times as they wish during their lifetime. However, if the subsequent will was made when the person was not of sound mind then it would be considered void and the prior will would be considered for succession.

You can challenge the will in court if the same been made under Coercion, undue influence, fraud, misrepresentation or mistake.

The Autor of the will was free to revoke the old will and execute a new will; as appears to have been done in this case.

The new will is a registered instrument; and hence it would be very difficult to stake a successful challenge to the said instrument, unless you have sufficient evidence to prove that this new will was made under duress and coercion. 

If there is any doubt about the Will, it has to be legally challenged at the court having proper jurisdiction, duly supported by solid evidence, in consultation with a lawyer. Mere allegations may not bring justice.