1. The WILL executed by your deceased mother in favour of your sister is legally not acceptable, as she had only a lifeinterest over the property as per your father's wish through the WILL.

2.  As per your narration, your father wanted to beget the property to his children ( both son/s and daughter/s, as the case may be), after his wife's death.

3.  Mutation of the property in your mother's name in the municipality does not confer her the title over the property as patta is only a secondary document.

4.  Since you and your sister are the only legal heirs to succeed to the property, each of you is entitled to 1/2 share.

5.  Send a legal notice to your sister for partition of the property into two equal parts, one undivided part to you and the remaining undivided part to her.

6.  If there's no positive response, file a suit in the jurisdictional civil Court for declaration, partition and separate possession of the property by metes and bounds.

You need to challenge that will now in court on basis of fraud. First send legal notice to sister and proceed with filing suit if she disagree on your terms. 

Yes you can rely on fathers will in the present suit but first you need to challenge that fraudulent will. 

Mother has only life interest in property 

she could not bequeath property to your sister 

on mother demise property would devolve on you and your sister equally 

mother will is not valid 

1. Your mother had living right only on the said property and your late father had not bequeathed the title of the property i her favour.

2. Nobody can transfer better title than what he/she has for which your mother can not execute any will bequeathing the title of the said property in favour of your sister.

3. Challenge the said will after the demise of your mother if your sister claims title of the said property based on the said invalid will executed by your mother.

- Since, your mother is not the owner of the property left by your father ,and further by way of WILL she was having only right to live , then legally the WILL executed by mother is not having any legal value in the eye of law. 

If your father's Will says your mother has no right to alienate the property, the Will made in your sister's name is legally not valid. You have to challenge your mother's Will.

Challenge the transfer to your sister.

The WILL has to be proved before the Court.

G.RAJAGANAPATHY 

High Court of Madras 

1. FIRSTLY file Probate Proceedings of Father's WILL, in Court & obtain Probate Decree, in your favor.
2. SECONDLY, file Eviction Suit against Sister in local Civil Court.

3. Mother having "ONLY RESIDING RIGHTS"  CANNOT execute any will of Property.

Keep Smiling .... Hemant Agarwal
Visit: www.chshelpforum.com

If you feel that your right to a share in the property has been deprived then you can approach court of law with a  suit for partition seeking the relief of partition and separate possession of your rightful share in the property left behind by your father.

As per your father's Will, your mother has only life interest in the property and she has not been empowered to alienate the property hence you can claim your rights in the property but only after the lifetime of your mother and not before that.