Process for removing my sister name in dv case

My wife filed DV case and she has dragged my sister's name who got married me and has been residing with her husband at different state since then.She met my wife only during my marriage.She alleges that on phone call my sister has harrassed her for dowry only one time.What can be done to remove her name.The case is in first hearing stage.My sister has a 1 year child.Your guidance will be highly appreciated