[otrs] Modifying service in the response form ?

Hello OTRS fans, I'm loking for a way to enable the possibility for an agent to modify the service (and maybe other fields) when replying to a ticket using one of the default responses. There is no such parameter in Config Options: Ticket -> Frontend::Agent::Ticket::ViewCompose What I'm trying to do is to fully qualify the new ticket as soon as possible. The first answer of the agent seems to be the right place, doesn't it ? What are YOU doing ? When do you fully qualify a new ticket ? For example, an email ticket pushed with Postmaster ? Thanks and regards, Régis