Aunt's share of the property gifted to her by my grandfather

My late grandfather got some land from my late grandmother's family after marriage. They both had two children, my dad (who died in 1993) & my aunt (who died in 2014). My brother & myself are the only two grand children to my grandfather. My aunt and her husband do not have any children or legal heirs. My grandfather gifted 3 acres of land to my aunt after my dad's death. He had registered the gift deed and accordingly transferred the land documents and passbooks onto her name. Just before his death in 2010, my grandfather registerd a will naming the two of us brothers as the legal heirs to all his land (minus the 3 acres given to my aunt). Forward a couple of years, my aunt's husband died in 2012 and my aunt passed away in 2014. Just before her death, she was taken to a hospital by her brother-in-law(aunt's husband's brother) and few days later she died in the hospital. At the time of the funeral, we were informed by the brother-in-law that she had written a will in the hospital naming him as the legal heir to her 3 acres of land as she has no children and her husband passes away before. The will was registered in the local sub registrar's office during her stay in the hospital. He took possession of her house, all the belongings, her car and land which were mentioned in the will. My questions are as follows 1. Is this considered ancestral property? 2. The will says 3 acres In the first paragraph, then becomes 3.6 and then 3.8 mysteriously, most likely typing error. The will says that the brother in law is being considered the heir as they have no children. Is this right? 3. We know for a fact that she was very sick and delirious and not in her full senses during her stay. Because of the amputation to her leg, she was not in a position to walk to a registrar's office to register the will. It really looks like the brother in law took advantage of the situation to get hold of the property. The will clearly states that she was in good health physically and mentally when she wrote the will and that she registered it at the registrar office in person. Knowing her condition, we seriously doubt that. 4. Even if we assume that her health permitted her to write a will, does the brother-in-law have the complete authority now or do we both brothers as the legal heirs to our grand father's property have a chance in court to get the 3 acres back if this is considered ancestral? is there a way for us to stop him from registering the land onto his name or selling it to others. My grand father was of the opinion that the 3 acres gifted to my aunt should come back to us after her demise but did not put it in writing. Kindly advice if we have a chance to fight in court or is the brother-in-law the rightful heir to her share of the land even if he did it unethically.