OBJECTION ON MY GRANDFATHER RESITERED WILL

Good Evening Dear Sir/Mam .This is Ashutosh shukla . straight away coming to point my grandfather made registered will in favour of my Father and he died in 15 year back that time my grandmother was alive so for my father was waiting if his brothers will take responsibility of my grandmother then my father will not submit the will but none of his brothers gives a single penny during oldage or even in cremation of her. So 2 years back when my grandmother passed away my father went to submit registered will his brothers are claiming that will is false will and made objection. My case is under trial on tehsil level but nayab tehsil dar not even responding even he is not sitting in office for hearing trial. Please help me out how to approach this case .also note all witness during making of registered will are as of now alive and ready to give statement in my favour