Your problem is the mesh.
Poser works best with quads,and you have all tris.

Tris are good for dynamic clothing, but a nightmare for conforming clothing.

Doc Geep has some vey good tutorials on the grouping editor.
I do not have the link right here but do a forum search for Grouping editor and Geep
as name.

First you ahve to remove all polygons from the left and right buttocks and thights groups that touch each other.
Then yu have to add these polygons to the hip actor and click the weld button in poser.
Do it front and back.

But for conforming? Build a mesh in quads.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
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