I noticed something while using Fitting Room.  Older content may be divided into multiple sections.  It is a technique used to create sharp edges at seams and other points on clothes.  If the clothing has such sections, Somooth or Smooth Fit option may cause the clothing to come apart.

So that, such seams must be excluded from weight map painting.

And, I had to draw a complicated map even in Fitting Room after all.  Simply adjusting Prefit and Tighten or other values was not enough to properly fit clothing from different figures to LaFemme2.

Fitting Room screen frequently freezes (on my old Mac), and users can't check the status of the deform unless clicking Fit button.  I won't use Fitting Room until it can convert clothes with a single touch using AI or something.

At any rate, it's useful how users can deform clothes with Scaling, Posing, Morph tool and Magnets.  Possibly, dress-up doll plays aren't fun unless users can choose from variety outfits.  I hope users will enjoy creating content by hand, like a craft, using this method.

I tried deforming this costume again using only Poser without my 3D modeler. Little Wizard Outfit for Mavka by Porthos (No longer available)

Next, I may try learning about HDRI and the ambient occlusion shader in Poser.