I think I am more confused by your question than by the game situation you are trying to solve, but I will attempt to shed some light on the issue.
Military forces in TYW are (from smallest to largest) 'units' (individual regiments and squadrons), 'groups' (several regiments/squadrons under a single commander) and 'wings' (several groups operating under a single general).
'Groups' are therefore sub-formations within a 'wing'. The purpose of groups is to reduce the number of command points necessary to lead the wing in combat. A large wing will have 3-4 groups along with supply, artillery and perhaps cavalry units attached but not assigned to a group. Wings without enough command points will suffer a combat penalty (shown as a negative % in the wing's tab). Since military forces are expensive to raise and replace, fighting with a command point penalty should be avoided as much as possible! Small forces - garrisons and security units - may have to fight without a commander, however, since each side has a limited pool of leaders.
Generally speaking, each side in the conflict will have their forces organized into 1-3 wings each led by a 3-star or senior 2-star general. Effective combat power of each wing will be 1000-2000 points, depending on strategic and supply considerations. Larger forces require more supplies and may be subject to movement penalties.
Hope this helps and good luck!