Share given to my father in family partition through a notary document

My dad has 4 brother and in family partition one my uncle gave his portion of share in a house in the name of a my father. This is notarized on a RS 50 stamp paper and it was mentioned that my uncle has sold his portion to my dad for some amount and he and his legal heirs will not have any objection if my dad will do any construction and use his share. It was also mentioned that my uncle has promised that he will execute sale deed in future. Time to execute sale deed was not mentioned. This was done in year 2000. My dad has requested my uncle on several occasions to execute the sale deed directly and through close relatives as well but Everytime he mentioned will do it in future. Now after 20 years he is still promising for future and we get to know that he and his sons wants more money out of that. We are the residents of that property for last 20 years and we have the possession of it. Below are my questions 1. Is my uncle still have rights to claim his share in the property? 2. In muncipal records his name is registered on the records but we are filling the house tax. 3. Is there any law which can skip my uncle and gave rights to my dad to register a sale deed for whole in favor of other party in case we want to sale this property? 4. How strong will the case if my uncle challenge for his portion in court? 5. Can we send them legal notice and ask for the execution of the promise he did? 6. Any other help or advice where my dad can claim the title of the property. Your guidance and help much appreciated.