Hindu succession - is this possible?

Is this possible?

We are 2 sisters. While I stay in India, my sister stays in USA.

My father owned 2 properties. One of which was acquired by him through his own resources (property A) and another one was inherited by him- Property B (originally owned and built by my grandfather).

During my father’s lifetime, my mother also passed away and I was looking after his health till his death.

Subsequent to our father’s death, as per his written “WILL”, Property A went to my sister and Property B came to me. Accordingly, my sister got her share (Property A) transferred in her name and gave me a No objection certificate for transfer of Property B in my name. The No objection certificate was attested by the consulate in USA. As on today, the mutation of the Property A is in her name and Leasehold Property B, in the books of records in L&DO and MCD, is in my name.

 Having sold her Property A, my sister now wants a share from Property B also. She claims that since this is an Ancestral property, our father could not “Will” Property B exclusively to me and as per Hindu Succession Act, it needs to be divided between both of us.

My questions:

Is her claim valid?

Is she entitled to a share in Property B even after giving a NO Objection, based on which the substitution of the property was done in my name?

What are the safeguards to be taken by me?

How do I handle this situation?