After a longer time of render-abstinence I did a picture again. The next pictures show the result of weighted shrink-wrap with a hi-poly tri-mesh I got from Elvaerwyn. Using the changed mhx2 exporter it now works without problem using triangles, when I select vertices in Blender.
So after being sure that no skin was outside the dress (e.g. nipples), I activated shrink-wrap to follow the body. But this time only for parts of the dress, so that no latex-dress was created. Here is the weight-painting of Elvs dress (excluding the zipper at the back):
Red means "follow the body" and blue "stay as you are". It works rather fine until arms or hands are touching the painted areas. Unfortunately the complete body is selected as object to shrink to, maybe a duplicated and animated but invisible body without arms, head and feet might even work better ..., but I managed it at least.
Btw.: Evi changed a bit in face region, I used blender to move the eyebrows to this lower location. Until now, no target is able to simulate this (maybe I will add a target somewhen), but slowly Evi matches more and more the original girl, whoever that may be.
Thanx a lot for the dress, Elv