create a will according to his wish to only son?

These are the words of the Supreme Court of India you can be called one of the guardian being a family member (son of your father who inherited this property from his father) hence your claim for adverse possession against the real owners your father & his brother wont stand the test of adverse possession. In your case the disputed immovable property was being owned by your grandfather & after his death you have been staying there with your father but your uncles (father's brothers) were not staying there. Now you’re these uncles want to sell off this property & you want to have your share out of it. Legally if this was a self acquired property of a Hindu i.e. your grandfather & if he died intestate i.e. without leaving a 'Will' or any such Testamentary document in favor of anyone, then by rule of Hindu Succession this property goes to his widow, all his sons & daughters, sons & daughters of predeceased sons or daughters in equal share. As you state your father is still alive hence you do not get any share out of this property. However if this was a Hindu ancestral property, you by birth get a share in this property being one of the Coparcener of this Hindu Joint Family.
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sell house fast