I know that someone already suggested a "flip all wounded units" option, that had among others the disadvantages of not allowing the player to direct his RP where he most needs them.
However at least to me a "flip all units in an army" would be a welcome addition.
For instance, I am pushing hard I German army, incurred some losses, but want to continue forcing with this army. Instead of selecting each I army corps separately, I could simply select a "flip all wounded units of this army" option - simplicity and flexibility combined...
Regards