No. You can have only one demat account under RGESS across depositories That is either NSDL/CSDL.
be away from RGESS scheme. Its a scam.
The process followed by DP(ISSL) and zerodha in handling this is totally ancient which invlove submitting document by courier everytime you make a transactions. You are likely to suffer a huge loss in this(1.5 Lakhs) and all for a mere saving of 3,5,7K