Would it be possible to add the following logic to SDP when it receives incoming email?
When fetching email for an open ticket, if the email is from a technician watching the group the ticket is in and technician is not the requestor, process the email as a technician's reply to the ticket and notify the requestor. Else process the email as designed (as a requestor's reply).
The majority of our technicians are not at their computers most of the day so having the ability to reply to a ticket via email would help them immensely.