DRM on the (I)IFT are generally "per attack." For example, no matter how many units are encircled in the firegroup, the DRM is +1. Likewise no matter how many units are using FFMO, the DRM is -1. If there is an effect due to the number of units, the DRM will say "per squad" or similar, e.g. for overstacking. The (somewhat unwritten) principle for attacker DRM is that you figure the DRM for each attacker, then take the maximum value of each DRM type. So if one attacker has a +2 hindrance, another +1 and a third +0, the attack of the three units as a firegroup has a hindrance DRM of +2. Similarly if one stack is overstacked by one squad and another is overstacked by two, the DRM for the attack as a firegroup is +2, not +3. The rules covering this are A7.52, A7.3 & A.5.
JR
