Errors in will of deceased sister

According, to the situation you're dealing with let me inform you about 5 errors that could make a Will invalid here in India. These errors are as follows:-

A Will Not Attested By Witnesses —
A will becomes invalid if it is not attested by at least two witnesses. In a famous case of Narinder Singh Rao, his father died leaving a piece of paper stating that his wife could inherit all his fortune. The will, signed by a single witness, was not registered. Interestingly, the Supreme Court ruled that the will was invalid because it was not attested by two witnesses.

Will Not Signed By the Testator —
A will may have all the valid components but if it is not signed by the person who is making it, it will be termed illegal. The will makers thumb impression is enough to make the will valid.

A Will Procured By Forgery, Coercion or Fraud —
Cases have been reported where wills have been made under undue influence or fraud. If this matter is proved in court of law, the will becomes invalid.

The Testator is of Unsound Mind or Below 18 Years —
Law states that a person who is in the right frame of mind can make a will. If he is of a sound mind, only then he can take the right decision of how to bequeath his property after he is gone. Similarly, a minor is in no position to take informed decisions. The law forbades him/her to make a will.

A Will has Not Been Dated —
A will may have been attested by two witnesses and duly signed by the testator but if it's not dated, it becomes void. The law also says that a new will with a later date would make the previous one null and void.

If a will is termed invalid, the court distributes the property as if no will ever existed. This distribution follows intestacy laws and is guided by familial relationships.

In case, any of the errors listed above is there in a Will of the deceased person, then the his/her Will shall be considered as Invalid.
And since, none of the above-mentioned errors are there in your deceased sister's will, you're good to go.

Now, coming to the inheritance and succession part, let me tell you that, Section 15(1) of the Hindu Succession Act, 1925 lays down the order by which a deceased woman's General Property is inherited :-

a) Firstly to sons and daughters, including children of any pre-deceased son or daughter, and the husband;
b) Next, to the heirs of the husband;
c) Then, to the mother and father;
d) Next, to the heirs of father; and
e) Finally, to the heirs of mother.

Since, you mentioned that you're sister was never married the situation given in clause (a) and (b) of section 15(1) of the Hindu Succession Act, 1925 does not stand a chance. Therefore, legally you'll be the inherent of her property.

Inform this legal information to the society members who are creating an issue, and in case they still oppose or create any sort of hindrance, you shall take the matter to nearest police station.

If that doesn't seem to help, you may contest for the property through filing a petition in competent court (where you can also get "Legal Validity" to your sister's WILL).

Hope It Helps

Regards
Kevin M. Paul