This is another rule that I intend to include in my proposed brief rules supplement:-
"Combining light troops
Some ancient armies including the Numidians, Spanish and Successors included very numerous light troops who fought in large masses.
To represent these, before the battle starts, two identical light units may combine to form a combined unit. Players may not combine units of lights from different lines in an army list, except where specifically mentioned in an army list.
Such units have two hits, becoming disordered after a single hit and lost after a second, in which case two medals are surrendered. Combined units count as two units for purposes of sharing boxes – no other unit can be in a box with them. The combined unit has the ammunition of the two component light units, so combined light infantry with javelins will typically have four ammunition and with bows, six.
For movement, melee and evade purposes combined lights act as the equivalent lights units except that when they are armed with javelin or lance, they may frontally charge formed troops. This is an exception to the normal rule for light troops which does not permit this. Combined lights are not required to evade when charged but may, however, still choose to evade.
Combining light troops permits the representation of peltastoi and thureophoroi fighting as euzanoi in open formation, armed with javelins. It also gives a greater offensive capability to javelin and lance-armed light horse."
I'd welcome thoughts.