Share transfer & capital gain

Hello all...

I have a quaery regarding transfer of shares & taxability of sale of such transfered shares.

Query:

I have demat a/c in one DP & my grandfather have demat a/c in another DP. Now my grandfather wants to transfer all the shares from his demat a/c to my demat a/c. And thereafter I want to sell all that shares within 1 month of such transfer. Now I want to know in which way can he transfer the shares i.e gift or off market transfer, so that my tax liability is minimum. (Note: all the shares in my grandfather's demat a/c are of more than one year)

Kindly provide accurate answer with relevant section/case law etc..

Thank you.