Found last will after 30 years of Grandfather's death

Hi, My grandfather had one son and one daughter and he wrote a WILL in favor of his son for his self acquired property. This will was not registered but it was in bond paper with 2 witnesses. He passed away 30 years back and somehow WILL got last in the house and we found it recently when we were doing house renovation. can this WILL be valid document to transfer the property title to may father? Can court accept this WILL after 30 years? If I go for probate, is it mandatory to summon my aunt to the proceedings? or can I go with probate that my mother is challenging the WILL which is favorable than aunt.