Question: Should NLOS systems count toward Arty overload?

[Mobhack]

Artillery overload is done by totalling the appropriate unit by unit class, i.e the indirect fire unit classes plus ammo carriers.

NLOS ATGM is a weapon class, not a unit class. There is no specific "NLOS firer" unit class since any unit can have the weapon, just like any unit could have a pistol.

NLOS ATGM are only used by humans. If you are playing the AI, use your own house rules, and if its a PBEM then come to a pre-match agreement on the things with your opponent.