Woman does not want to return to her husband's home
Q: If someone's sister is married, and after marriage she is living in her mothers home due to instability with her in-laws and husband. Now her elder brother and his wife (who dislikes the sister) are pushing the sister to go back to her in-laws (husbands) home, but she is refusing to go back and says that when her husband will come back she will go (her husband is living in another country). But now her elder brothers wife has gone to her parents home and is demending a divorce (the elder brother got married 3 years ago and has no children). Please expain us what to do as per islamic laws.