My house possession is slowly captured by my sister help me

Hello all the respectable member of this Forum and specially the Lawyers . I need an Urgent Suggestion on one disputes where I am facing problem . I have a 2 Floor house in Kolkata . My Father deceased on 2010 leaving behind a WILL in my name for the whole house . We are 4 Children of our Parents . 3 Sisters and 1 brother . I am the only Son and Yongest Child of my Parents. My Father explained in the WILL clearly that he spend enough Money for the Marriage of my all 3 sisters . They are well settled . Even he invested some money for them and Provided them as Well . Only he left for his Son is his Business and his house . Where no other children can claim anything . Now I live abroad for my job . One of my sister ( Eldest one ) is married but she lives in our House for Long time as she was facing problem with her parent-in-law . So father was initially supported . But later she remain in our house Forceably . My father was not wishing sincreate about this matter. So he was not moving for the Court ever to drag her out of the house . Now she Occupied the whole 1st Floor . Where I have my own room with all my Furniture . Now my eldest sister is planning to give marraige to her Son . So she is trying to remove all my Furniture and give than Room to the Son . Though I did a BIG mistake for that I am taking apology to all . I never lock the room on good faith . As I kept a servant who clean the floor and room . So if it locked it can be a BIG Problem . I didn't realise that it will happen. As my sister and her Family was never staying in that room . Keeping it vacant for me and my wife . Now she is trying to Occupy . Can I take some Legal Step to stop this Forceable action . Even she didn't inform me . I got the Information from my another sister who visited the house every weekend . Also another point here I was sending her Enviction Notice from the Lawyer in 2014 . She didn't respond regarding the Notice and never taken any action . Can it help anyhow ? Also is there any legal way I can remove her from the house . As the House is having WILL and it is Pending in Court for Probate Verdict . In such Situation what can be done . Please can anybody help me with any Suggestion, Advice and Guidance . Is there any Caluse in Property law by which I can stop her taking such action . Please also mention the Clause number or Reference .