Possession of agriculture land

Sir, My mother purchased a agriculture land from a relative in a village in the year 2000 who are two brothers.we purchased a land from younger brother who got half share in it land and got patta pass books. and the records are all updated on my mother name and we got pass books all pahanis are updated till 2017. Now the elder brother is creating the problem and forcing us to sell the land to him in low price which is not acceptable to my mother and she came to agreement with other third party with market price. we applied for a new passbook according to the govt.order under the rythu bandhu scheme but MRO refused to give us new pass books and said, prove your possession and ask for the new passbooks. My questions are as follows: 1.How do we take possession of that land...? 2.what if he is cultivating our land with out our notice....? 3. if he stops us to enter in the land what should we do? do we have to approach the police? 4. Do MRO have any right to stop issuing our new pass books. if he does what should we do.?