Family Property Duspute among brothers to split the common land

my grandfather and his 4 brothers have common land which is owned by their parents and they passed away and one among brothers filled a case stating that he need that land but actually it should be split into 5 now case lodged person ( one brother )also died. now an unknown person coming and saying that he gave 3lakhs to the dead person and bought the land when he was alive. it a common property for 5 of them, in this case, what can we do??? the new person will not have any rights to claim property rights because it is a common property for 5 brothers right???? in this case what is law and sections to be procced. and what should be done