The INJ system depends on having the basic morph structure in the .cr2 file, so the V3 morph "FootArch" is already in the file. The INJ pose adds the deltas for the morph, and changes the settings to make the parameter dial visible. But SP3 doesn't have that basic structure in the file. As for where the parameter dial appears, it probably means the morph affects more than one body part, most obviously both feet