Uncle needs Share out of my father's own property

Good Morning! We have 3 plots(A,B,C) in our village. A & B are in my father's name of his own.C is in my father and uncle's(Father's younger brother, who is not alive) name.After death of my uncle, aunt sold her share to my father before 15 years.Only hand written paper is available.Till now that plot is not transfers to my father's name due to certain reason. As our three plots are being acquired by National Highway project, now my Aunt and their children are demanding share from us and raised complaints at Land Acquision office not to process our papers.The documentation process is on hold now. Request you to clear my below queries: 1. In case they file a court case, can they get share from all the 3 plots? 2. Is hand written document is valid at court of plot C. 3.In case they are eligible to get share from plot C, how much they will get.Either share from only land or also from the building which is build by us. 4.Can my father's sisters can demand share from all of these plot. My grandfather dies on 1997.No plot is in his name.