For BSE this has to be done manually for each UCC profile from Invest Online BSE >> Profile list menu >> Click on Authenticate Nominee from the actions on the right.
A new page will open which will show the list of Nominee available in this UCC with Relation and Share %. You need verify the same and then click on Save button.
Then ask the investor to click on the link received on mail and trigger and enter the OTP.
Once you've sent this to all your clients, you need to download and upload the UCC text file from BSE into Investwell to update the Nominee authenticated status so that the action is removed from Profile list from those clients who have done Nominee authentication.