The idea here is that VASSAL could support the concept of having major and minor hexes or hexes and sub hexes and units and sub units. The way this might work is that a major hex might be some multiple of the minor hexes, say a multiple of 3. At a certain map scale one would see just the major hexes and the major units. When on zooms to a more magnified map scale then on might see both major and minor hexes and units or just the minor ones. When moving a major unit all its sub units move with it automatically (unless split off as another group). When one zooms down to the level one can see the sub hexes then one can place the minor units on any hex in the sub hex (or adjacent (or whatever rule some wants to employ.
With this feature one can operate say at a platoon level and move platoons around using say a 150 meter hex and then zoom in to a squad level where there is now 50 meter hexes and the player can deploy those squads that make up that platoon however the rules permit.
I can see even doing this at three levels … any more than that might become a bit problematic. Thus one might go up and add a company level of hex and unit or down and add a section or single man level… though for the later maybe having decks that can be mapped to individual hexes may be a better way to go.