Demat account query

A user is asking for clarification on linking their wife's existing HDFC Demat account to a new NRE/NRO account, given they have been living abroad for 15 years. They want to know if the current Demat account can be linked directly or if it needs to be dissolved and a new one opened. The advice given is to convert the existing savings account to an NRO account and then link the Demat account, provided the customer ID remains the same.