When using the fitting room, first zero your figure and the item of clothing before entering the fitting room.  Make the necessary adjustments, go back to the Poser room and save.  Create a new scene, import your figure, zero first, then load your clothing.  See if this fixes the problem.

My recommendation for overlapping conforming clothes, use Poser's morphing brush to paint a loose fit over the capris.  However, this should be done after the final posing of the figure, never from the T stance.  The cloth room can perform multi-layering but they must be performed in separate simulation.  A problem that can arise, however, is how the conforming clothing is constructed and meshed.  If there are too many separate sections to the mesh, the clothing will fail during the cloth simulation.