Well, I played around with Dina and the corset for a while. One thing I noticed is that it matters that IK is set the same way for both the figure and the corset. Like all Poser figures, Dina defaults to having the right and left leg IK turned on (there doesn't seem to be a way to defeat this... if you turn it off in the .cr2 Poser turns it back on anyway). If you leave it on and then conform the corset, also leaving IK on, it works as it should. If IK is off for both the corset and Dina, it also works fine. If IK is off for Dina and on for the corset, then when you apply the MAT pose the stockings start acting strange. I have no idea why. It must be a Poser bug, because the MAT poses have nothing in them but material assignments. I was not able to reproduce the problem with the frill materials not getting assigned properly. You might try deleting the .rsr files from RuntimeGeometriesdcClothingdcCorsetDina and see if that helps.