Whether the ski is edge locked or railed or if it is brushing has to do with degree of edge angle . I never referred to an ski breaking out of an edge locked carve. I recently went out with one of my ski supervisors (former ss director and psia level 3) and we did some super phantom brushed carves. I asked him how much steering we used and his answer, none. YM
The difference between a PM and a SPM has to do with carving. Since we cannot agree on what a "brushed carve" is, the discussion is not going anywhere soon. However, for others reading through these postings I can point out that in the pre-carving ski time era the PM was used as an alternative to up-unweighting to initiate brushed turns. When the carving revolution began and we started to "tip to turn" TTT and no other movement or technique was required the outside ski release and tipping elements used in the PM were still adapted and called the SPM. So if you are brushing your turns you use the PM, if you are carving your turns you use the SPM. The SPM is the same as a OLR/OLF. Flex to release retraction turn with active inside ski tipping.
Steering needs to be IMHO divided into two categories: active and passive. A classic large to medium sized parallel turn initiated by up-unweighting has very little to no active steering present. You simply pivot the skis into a minimal to very small brushing angle at initiation and then you ride the arc through by maintaining balance and edging. Your skis are steering but its not because of any direct turning of the feet leg action. Just like in a wedge turn. However, when you are trying to make smaller radius turns aka short turns you need to not only initiate a brushing angle at initiation, which does not need an up-unweighting leg extension because you are using the momentum from previous turn as mentioned earlier, but also pivot the skis quicker through the turn. Here you use leg turning. Some also call it a wind up and release but in bumps for example you need to be cranking those feet from side to side sometimes very quickly.