In an effort to avoid using Aiko or Girl FBMs as I set up an existing character on a "fresh" S-16 base, I found that I could use a few of S-16's SCALING dials to get a similar shape (narrower waist, fuller hips).

But when I loaded a "fresh" uniform skirt for the character (which is the skirt from V4's Classic Dress 2 with a custom plaid texture), I found that the skirt did not "follow" S-16's Hip xScale and Hip zScale values. I had already applied the "Copy Joint Centers" pose file and had checked "Include Scales" when conforming, and the skirt did follow other scaling. The only relevant FMB dialed in was Bulk, which the skirt came with.

The weird thing is that it isn't just a case of the skirt not scaling up to match the figure's 102% values on Hip x and z scales. The skirt actually seems to shift slightly on the +x axis, so that only the right side of the figure's hip pokes through the skirt mesh, as you can see in the attached renders.

I have a feeling the problem might be in the skirt's rigging, rather than in S-16's, but I don't know enough about how these things work to figure that out. I ended up just setting the character's Hip scaling back to 100%, which is fine, but I still want to know what causes this kind of problem and how best to resolve it. (So that 20 years from now, I'll finally be skilled enough to make V4 outfits that work exactly the way every user expects them to, if there are any users left...! )