Name change of share certificate

Mr A bought share in Hindustan unilever ltd in 1940 and he expired in 2000,but he didn't transfer share or mentioned any nominees.
Now if any of his legal heir want to get the share certificate to be transfer to his name 1.what is the procedure as per Hindustan unliever ltd  ?
2.If the legal heir want to sell the share after the share transfer want is the procedure ?