We run a bulk maintenance update on the 15th of each month which adds the code, then a query is ran in Pathway that selects those accounts and uploads onto the letter template. We then print the letters all at once and hand over to the internal printers to envelope and mail.
have you tried placing a call to Civica or any Council using Civica to see if a similar process can be implemented. Surely its just a field missing from the letter template, and maybe there is something that needs to be switched on in the back end to produce them in bulk.
