help me-Is it possible?

Yes, you can have a joint account for Demat

or you can give the relevant authorities to your dad, with a letter of authorization

Ya you can do but you have to decide
 

whether you want to become as a first member or not

wel pratik....i think rushikesh had solve ur problem.... 

there is form for addation of another name in your demat account, fill it and submit, they will change your status

what i found that u can only add nomination name or can edit itafter openning an account.

But once u opened account then you will only be allowed to remove the one of the holders name only in case of Death or Unsoundness declared.And that will also required approval for the same.