Shiloh Scenario Question

[scout1]

SHould I be surprised by the following or is it that I haven't a clue what I'm doing ....

1) Buell starts inactive
2) Grant (Army of Tenn) starts active but has NO ONE assigned to it other than a signal unit
3) At the very start, can't assign anyone to Grant's Army. Bunch of units are in the same general region, just can't figure out how to assign ....
4) OT question for this scenario, can you assign any unit, anywhere on the map to ANY Army, anywhere else on the map ? Wouldn't choose to do this, just curious ....

[scout1]

OK, Sherman is at least active from the get go, but can't have him join Grant's army either. Just seems odd to have an Army Command at the start without an Army assigned to go with it.... Or am I missing something ?