Succession law

Sir, My father died earlier than my grand mother. My grandfather at the time was not alive. My father when died left two sons, widow(my mother) and host of uncles and aunts including my grand mother. My father and my mother along with two sons ie me and my brother use to live separately in a property owned and made by my father himself. After his death until now which about 30 years the property is still in my fathers name. We haven't had done the succession on property yet. My grandmother passed away 10 years back. All of sudden now one of my uncles has gotten us summon from court saying 1/4 of my grandmothers share is due as inheritance to remaining 3 brothers of my father and one sister of my father. All this while I must mention we only lived in the property that is two sons and mother. In fact after my fathers death all the installments to the corporation for the dues of the property were made by my mother. We want to ask u that except this uncle the two other brother and sister of my father are ready to give up their share if at all they have a claim in written in front of magistrate against this summon to us three legal heirs. In this situation does our uncle who has brought upon this case stand a chance to claim 1/4 of my grandmother share in property which in itself is 1/4 of the original property. As far as we know there is no will of our grandmother. And let's say if there is one does it entitle him anything. Kindly advise.