I had hree brhers One f hem died inesae ab 18 years back A sccessin cerificae menining he names f my

I had three brothers. One of them died intestate about 18 years back. A succession certificate mentioning the names of my 2 surviving brothers and myself was obtained from the competent court, mentioning all assets and liabilities including description of shares of a company. But successors did not bother about the shares and hence remained unclaimed. In the meantime value of shares has jumped to 50 lakhs or more. An year back, one of the successor brothers also expired intestate and he is survived by a son and a daughter. Questions are :- (1) In case of the brother who expired last year, are his legal heirs (son and daughter) entitled to the share he owned in the stocks of the said company or their share stands extinguished with his death ? (2) In case his legal heirs are entitled, how to include their names in the succession certificate ?