I suggest to extend the configuration of the email WOH and change the semantics of the variables containing mail addresses:
add an optional cc for carbon copy
add an optional bcc for blind carbon copy
add support for more than one mail address in to, cc and bcc at least as commaseparated lists in one variable.
you might add a variable for the delimiter, defaulting to ',', if I read the Admin UI right.
My needs would be: There a several organizers of a series. If a workflow terminates and the event being processed belongs to such a series, a mail should be sent to them. The Admin should receive a blind copy of such a mail.
As far as I can see, the Admin UI supports multivalued fields, e.g. Organizers and store them as a string with ',' between the items.