See what I mean? Semi-dynamic is rather unconventional and many don't know how it works. These 2 dresses I have mentioned work both as conforming and semi-dynamic, but I guess most people will use them as conforming.
Semi-dynamic works like this: you conform the outfit as usual. The select the lower group, which could be hip or pelvis, and switch to the Cloth Room. Create a new sim and when you get to Clothify, the correct group should already be selected, assuming it was selected when you entered the Cloth Room. The only remaining part is to choose what body parts this part of the dress will collide against, and then start the simulation. By default, the Cloth Room will always revert the figure back to T-pose before running the simulation, but these 2 outfits in particular are fully conforming, so that is not necessary.
So the only part that is different from a fully dynamic outfit is that you simulate cloth on only 1 group from the outfit. In fully dynamic outfits, you select the whole outfit, since it's all 1-piece anyway. Conforming outfits have lots of parts, and we only simulate 1 of them. The groups have to be designed with this in mind, since most conforming dresses have the legs part split into multiple groups, and that won't work as semi-dynamic.