Sister denying to give property papers

Hello Its about my wife, who is entitled to ancestral property. Property chain as follows..gpa in the name of wife's mother, after her death four legal heirs 1 Father, 2. Elder sister 3. Younger sister 4. My wife youngest. Now father transfer his ¼ share by making Relinquishment deed equally to all sister which all agreed and signed and was registered. After father's death all sister decided to keep the documents simultaneously , in the meantime get the property freehold. Documents was with eldest sister. After few months when my wife asked for documents and extra keys of house they refused to handover. Few months later elder sister ranged and asked my wife to let middle sister to stay in the ancestral house. As they had deined for documents, my wife also denied permission to stay as she had lost faith on them cos they can now wanted to take physical possession, which later my wife would face hard consequences. What legal action should be taken plz advice. At present keys and documents are with elder sister, now she is forcing my wife to sell her share to them at there terms which is not acceptable to my wife. What should we do. Kindly advise. Thnx