Dispute on Land/Home property between brothers

Hi, My dad is an ex-army (and currently a teacher in a primary school), 30 years ago he and his brother bought a land with 50% monetary share (about 1100 sq ft land, bought at Rs 28000, paid in cash by both brothers Rs14000 each). However due to the absence of my dad (due to transferable job), during the purchase of land in Kolkata, it was registered in the name of his brother(my uncle). The house was constructed by my dad in 2002 and he invested all the money for its construction (except Rs 80000, which was paid by uncle). Even after repeated asking, uncle did not till date gave the rightful share to my dad of the land on paper. The land is still in my uncle's name. However we are the sole residents of the house for the past 12 years. My uncle never lived here, they have a house in a different city. Recently it has come up that he wants all the property to himself. All our official documents are entitled to this address (Voter id, Passport, Telephone bill etc). However the electricity bill is still on my uncle's name as only the land property holder's name can be on it. As was decided early that half of the property will belong to my dad and the other half of it will be for uncle. We have constructed only half of the house and stay there. the other half is partially built..and for the remaining half as well 80%of the investment is from my dad. My dad's two other younger brother also live nearby in their own houses. My dad has been paying the taxes of the house too (however in cash).Can you please suggest a way out of this tricky situation? What we are looking for is a viable settlement. We tried to offer them settlements (either 1) authorize us of our rightful property i.e half the land share and pay the amount my dad incurred while constructing the building on the other half which was built on my uncles consent or 2) sell the other half of the land to us at the current land price and we also pay the prices they payed with some interest...however he was reluctant with both) Regards,