Guidance regarding transmission of Demat account

Dear Sir/Madam, I am not sure if this is the right forum to raise this but I need advice and guidance regarding a question I have about transmission of shares in a demat account in the event of death of the sole account holder and the nominee. My grandfather held a demat account in his solo name, he had included my father as a nominee in the said demat account. My grandfather passed away a few years back and unfortunately, I also lost my father a couple of months back. While going through the files I notice that my father though being a nominee had failed to get these shares transferred to his name during his lifetime. The DP is not yet aware of my grandfather or father’s death. My father has left a will according to which my mother is entitled to all his assets. I do not have my grandfather’s will (I don’t even know if he ever made a will). My question here is can my mother now become the sole owner of these shares based on my father’s will because both my Grandfather (the sole owner of the demat account) and my Father (the nominee) have passed away, if yes then what is the procedure to get this done? Any advice or guidance in this regard will be much appreciated. You can write to me at [deleted] Thank you for your help. Regards, Gulnar