Support Units

[Judykator]

Does anyone can explain to me what is the circulation of "support units" in the game?
For example:
1) why there are support units possible to join the divisions - corps - army? Could it be that the divisions take support units from corps pool, corps from army pool, army from OKH pool?
2) whether these units are a common pool for all the corps and army?
3) whether the best way to support individuals moving from one unit to another is to first transfer it to OKH / Stavka and then in the next round it is available everywhere?

[Balou]

check this:

tm.asp?m=2911364

tm.asp?m=2884019

tm.asp?m=2841454