Transponder Code Changing/Flight Plan Changing
 

For big Boeings and Airbuses, thought that moving a stored flight plan to the active flight plan was done via the MCDU.

Didn't know that operating the transponder could cause a stored flight plan to become active (see below). Can the transponder code changing described below also be done via the MCDU?

"Certainly not outside the realms of possibility that, whilst transitioning from one code to another, that another flight-plan could be moved from "announced" to "active"".

Aviation Today :: Changing Transponder Codes

If i understand it correctly the article is about the ATC side of things, not on board stored flightplans. Receiving a wrong swawk while changing it could activate a flightplan in the ATC system that is not active yet.

But it seems to be written by someone who is missing some of the normal procedures, especially on ground of todays airports where an active (auto) transponder is required in many places.