Sir, We are two brothers and one sister. Elder Brother , Myself(Brijesh) and Younger Sister. My Father and my Elder brother have died , My mother is staying with my family , Her total care is taken by my family , Elder brother's family(two sons & Elder brother's wife) stays In a different location. My younger sister is married(have one son and a daughter) and stays with her in-laws. The Flat in which we stay is in my mother's name(100%) , she wants to make a "Will" , that after her death the Flat will be only owned(100%) by myself(Brijesh). She wants to register the "Will" , after my mother's death, can my brothers sons and my younger sister challenge the registered "Will". If yes then how can we deal with it.
Since she (your mother) is absolute owner of the flat, she may execute a will provided she is a Hindu, in disposing mind, maintaing good health and she is not under pressure, allurement, threat, coercion or any other extranous considration and get it registered / notarized.
One can not avoid risks/opposition/challenges from others, you can only take precautions and ensure that every thing is legally pucca. If you can get the signatures of the elder brother's wife and younger sister as witness to the will you may avoid such future litigation on challenge of such will.
(1) if the properly stamped and registered documents and the share certificate stand in your mother's name, she is the absolute owner and can Will the flat to you.
(2) In the event of a challenge to the Will claiming that the flat was purchased by your father, the defense would be that it is a gift to your mother out of natural love and affection hence she is the absolute owner.
(3) It will be prudent to get the flat nominated to your name besides the Will in your favour.