Agriculture land purchased and one of the his relative creating trouble

Dear sir, Land is belong to one gentleman(level-1) and he have 2 sons(level2), and one son again have 2 sons(level3). I purchased 6 acres of land from Level-3 legal heirs. total land belongs to Level-1 owner is 21 acres including road- without road 18 acres. unfortunately, one of the relative of (level3) cheated and altered records in revenue office and created passbooks(for 7 acres) on his wife name by mentioning that she also legal heir(one of the partner- at level2). now this 3rd person claiming that 6 acres of cultivated land is not there not allowing us to do cultivation for 6 acres. he saying that only 4.5 acres will be coming and remaining land goes to road. also asking us to do rectification sale dead. Not able to get support from revenue officer as he is a problematic person. he is not supporting to surveyor also. 1.Can we claim that this land have only 2 parts.( he is not actual legal heir).? 2.Even we are ready 4.7 acres of cultivation land , but he is not giving without ratification of sale dead. what should we do?