If you agree with using Inherent as SFF and FPF is clear SW limits is not so clear -except for this Q&A I suppose still valid-.. I mean even using TWO SW the unit may fire its Inherent FP as SFF and FPF with any of the weapons used before (if MGs).. I mean, if the limit of using TWO SWs is not taking in account when firing as SFF and FPF -a new limit is considered-, why is the limit of using ONLY ONE SW? Is not possible to use a diff SW but only ONE?
Even with the Q&A, IFP is retained vs adjacent targets in Final Fire, So it´s looking one of the originally two weapons fired may be forfeited to use IFP. It looks a German squad may fire a PF and a MMG, and then IFP and the MMG as SFF and FPF.. Or an American one a BAZ and a HMG and then IFP and HMG as SFF and FPF.
First of all, this is an interesting thread! There is a ton of subtlety to Defensive Fire Principles which (for me) can always benefit from this kind of discussion.
I think, the first point to consider is whether the MPh and DFPh are together considered
one phase for defensive fire purposes. A.15 suggests so, though saying that a unit may fire in both phases is not quite the same as saying these two phases count as one (I guess the above quoted Q&A supports that they are one). The reason this is significant is that SW usage (A7.35-7.353) is defined
per phase. So if a squad can fire two SWs or one SW plus its IFP in one phase, then THAT's IT! Once it fires an MMG AND its IFP, it can only continue to fire that MMG and/or IFP during SFF (as per the cited Q&A). Personally, I
think that the MPh and DFPh count as ONE PHASE for defensive fire purposes, so fire of both an MMG and IFP during First Fire would forfeit that unit's ability to use a second weapon during SFF, or Final Fire. As for FPF, see below...
Moreover, do remember certain restrictions during SFF, FPF, and Final Fire. Namely, that a unit firing during SFF can only use "small arms" MGs, and IFEs only,
or forfeit their use for the remainder of the player turn. Any usable MGs must use Sustained Fire penalties. During FPF, a unit MUST use all usable MGs/IFEs in its possession (A8.31... no exceptions given. So if a squad has two MGs/IFEs, it cannot use its IFP). This last point can be a detriment to a squad possessing two SWs as a squad with an MMG and an LMG will be forced to use both despite that its IFP plus MMG could perhaps garner more firepower.
I think, btw, the idea is that firepower is an abstraction of manpower, firepower and time. Once a unit commits to using a SW, some of its men are assumed to be firing that weapon (at specific targets) during an extended length of time. While they are theoretically free to switch to another weapon as the enemy maneuvers multiple units into or out of view, the rules force a player to decide where its elects to focus its "primary attention" (and, thus, its "effective fire" for game purposes). The exception that a unit can more freely use IFP at adjacent locations simply acknowledges that a unit would almost certainly take the opportunity to defend itself versus an threat which was moving in close.
Anyway, that's my two cents... thanks for the question (and discussion so far)!