Verbal property bifurcation and construction on it.

My father is the sole owner of a land property he bought after retirement to construct a family home, he was govt. servant, a pensioner and lives with my elder brother his wife and two kids in a rented flat, my mother lives alone in village on fathers money, i live separately from them in the same city on rent.. my wife lives in a hostel in the same city studying on fathers money too. we don't have livable construction at the village. Now, my elder brother with his wife and some relatives/neighbor staged a bifurcation plan in my absence and verbally got go ahead nod from my father (owner of the property) to construct his personal home on more than half the property. i have two sisters too. Is this verbal bifurcation and construction on it valid.? my elder brother and his wife claims that its their house and they only invested money, not my father. Its also to mention that my elder brother also uses fathers pension money for the flat rent, education of his kids, day-to-day expenses of his household. since i live separately, my wife live in the hostel, my mother lives in the village, one of my sister is in the same city. i want to move in, in this house with my mother and wife. kindly guide.