I still have huge problems with how my combat units are supplied. I always have enough rail capacity and depot capacity. I also have enough trucks in my pool. But as the screenshot here shows they do not use them in my depot. That means the combat units use their trucks and that cost me a lot of movement with them.

I now read that maybe there is a connection between HQ prio and Depot prio. Is it possible that a higher HQ prio would send my trucks first to the units and then to the depots? This would still not help a lot but I wonder if I could this way set HQ prio to a low level when they are close to a depot with their units in order to use their trucks for other places like depots with higher prio. Would that work?
But the main question still remains, how do I get my pool trucks into my depots?
