Tarnok
An Agent can add any Collaborator above the Response textbox and then use the %{ticket.thread.original}
variable anywhere in the Response textbox and that will populate the original (first) message in the reply the Agent sends.
Additionally, we have a variable that will print out the full ticket thread. You can edit your Response/Reply Template and add the variable %{ticket.thread.complete}
and when any Agent replies to any ticket (that uses this particular template set) the full thread will be sent to the configured recipients.
Cheers.