I'm not sure I completely understand your situation, why can't you control the supply-wagons?This was never resolved was it....I can't control half the wagons? I've found the advantage of resupplying, but it's like you have to schedule, make the time to do this? This is in single play mode.
Example - I have a custom OOB where I command all of the troops that are on the battlefield, so once the battle starts I place the four-wagons in the rear on the battle-line.
But, this requires that I Take-Command of them so that they do not follow the divisional-commander.
So, are the wagons that you are trying to command under your chain-of-command, or do they belong to a part of the army that you do not have control over?
davinci