What is proper line of action(Legal remedy) to resolve the matter?

Background: My mother purchased the land in 1996 and was cultivating it till 2014.The previous owner lodged various revenue and court cases claiming that part of land was sold by his father to some of his close relative, way back in 1978.There is no claim, revenue records till 2002 to support his or his relative’s claims. Till 2012, In all the cases launched by them at various levels up to high court/ Revenue commissioner, ultimately resulted in favor of my mother as the absolute owner of the property. Meanwhile the cases lodged by mother against the previous owner and his relative in lower courts were on from 2002 onwards. Till 2015 all the interim judgements were in her favor.(Opposite parties were restrained to enter the property.)In 2015,because of ill health and family problems ,She could not attend the court matters .The lower court (ex-party ) decided that the previous owner and his relatives are not the owners of the property but possessor of the land. In 2016, we lodged appeals against these judgements in District court. The cases are on in district courts till date. Meanwhile, the opposite party managed to have false mutation in favor of his relative for the part of land, based on misinterpretation of lower court judgement in 2018. SDM case was on from 2019 to 2020 .The decisions are in our favor. SDM concluded that mutation in 2018 in favor of his relative is wrong and to be cancelled. But meanwhile, opposite party-Relative sold the part of land based on 2018 mutation entry to the son of previous owner by the registered sale deed in 2020, when SDM decision was awaited and during pandemic situation . That resulted into new false mutation entry in 2020. The new headache and New SDM appeal. Please suggest suitable line of action to resolve the problem.