Release deed

My great grand father had 2 daughters only namely (lakshmamma and shardhamma) he died 12 years back without living any will beside . one of my grandmother field a partition suit they both sisters got their schedule property in court as schedule a and schedule b. My grandmother (lakshmamma) had one son and two daughters and one of them is my mother Son of lakshmamma had mouth cancer he died one year back But the thing is he has fraudulently executed a release deed from mother lakshmamma without knowingly because she is an illeterate and cannot read but she knows only to write her signature The said propertys the son of lakshmamma has executed the release deed is the share of lakshmamma both daughters but the property was in the name of lakshmamma itself now lakshmamma has filed a case in maintanence tribunal in front of assistant commissioner and he has passed an oreder for the opposit party What can the next step be taken and how can the assistant commissioner pass an order to opposite party when the release deed is executed fraudulently