Unit Transfer problem

[GodwinW]

Starting out my game I wanted to shuffle some unit compositions around.

I found out I cannot temporarily assign troops to units above their command to then switch them out for other units.
So I need a 3rd, empty unit to do it.
That's a bit of a hassle.

Luckily at the start all units are at the capital and the SHQ is empty so I assigned troops to it, planning to use him to swap the units around. Assigned troops to SHQ from both units I wanted to swap troops between and now comes the big problem:

I suddenly cannot remove the units from the SHQ anymore.
Game says something like "cannot reduce power of unit below 3", but the guy started at 0... So now I lost troops I can not use as I want.

[Saros]

You really shouldnt be manually modifying OOB's like this, you will recieve a big combat penalty for non-GR units in adhoc battlegroups like this.

[GodwinW]

Ok where can I learn more about this?
It was militia btw.

[Saros]

Oh for militia then go nuts I guess, I am not sure about there being a malus for them.

[GodwinW]

The manual says nothing about penalties.. Can you offer some more insight about this malus or penalty?

[Culthrasa]

One trick is to buy a few (regular) units with the SHQ (like some inf) so it has at least three remaining after you switch those other units out.
But beware, militia can't be put in a Battlegroup and they have their own OOB's. So about the only thing you can do with militia is put them in the SHQ and let them serve as replacements for other militia units or disband the subunits and get some population back. (this is what i found out, perhaps there is a way i don't know about )