Legal right on property of elder brother which he received vide g

Sir, 1. My father has three brothers one elder to him and other is younger to him. When the two brother were not born only elder one was born, my father grand mother executed a gift deed of all her property in the name of elder mother as she has no other heir except my father mother. Apprently to save the property from other sharer of my father maternal grandfather (viz brothers of maternal grandfather). 2. However maternal grandfather other sharer founght a long battle for declearing the deed null and void. My father through out his life fought the case against the property as he was living in the village and also considered it as joint property and also his elder brother was staying away for service. My father was also a party in that case and many of time his name figured in the case as alone he was fighting. Finally case was won in the lower court, and all the properties occupied. 3. Now came my father elder brother after retirement from the service and partition was done first between younger brother and elder brother/ my father(Jointly). After some years partition also took place between my father and elder brother, in which he signed partiton in the presence of village panchayat ,giving shares in each property ancestral as well as gifted property.My father has also did mutation of property in his name. 4. My father expired last year and my father elder brother developed greed on the property and preventing us from construction on the land site stating that property entirely belong to him as grandmother had surrendered the property in his name. One important point when this surrender did executed elder brother was minor, frankly i dont know my grandfather plan behind making this happen. 5. I would like to know the remedy and my legal right over the property which for almost 50 years we considered as joint and my father alone fought court battle for the property. Thanking u sir, waiting anxiously for early reply.