The idea is that there will be a special dynamics profile that will be calculated based on the dynamics written in the music, which will be converted automatically to the appropriate controller(s) or velocity according to the demands of the current playing technique on the current endpoint (i.e. switch within a patch or channel on a given virtual instrument). If you edit this data in Play mode, then additional hidden dynamics will be written into the score so that there is somewhere for this information to live in the existing dynamics profile.