Having problem after getting degree

dear sir/madam, my sister's husband has been dead.after her husband's death,she filed a partition suit against her husbands elder brother and her mother-in-law.now, she got judgment degree from court after 7 years.in that judgment, her husband's partition for her is 1/3 share property. while the suit was going on.my husbands elder brother and her mother-in-law made an sale agreement to a person.he Is MANIVANNAN(politicion).in that agreement they sale their 2/3 partition share.that property is a marriage hall.marriage hall is having 24000 square feet.built as one building.their 2/3 share is 16000 square feet. the person(MANIVANNAN) who brought their share is now occupying my sister's 1/3 share(8000 square feet) too.after getting degree she asked for her share.but he refused to give my sister's property.MANIVANNAN(politician) is threatening my sister.he do not allow my sister to enter her property.documents of her 1/3 partition share (8000 square feet) are in my sisters hand. now, what should she do? please, guide me...