Are you changing the correct file? When you start the game are you selecting "normal scenario end-date" or something else?
Anyway, you can also change the enddate in your savegame.
Anyway, you can also change the enddate in your savegame.
Is there a source of info regarding brigades: detaching (sometimes I'm allowed to do that, sometimes not), attaching them (never managed to accomplish that) and general info regarding them.