Thanks everyone.  It would seem though to me that the results should be consistent.  When I grab the thigh and do a side to side - the dress goes with it.

PhilC - in the first image I am moving the thigh side to side using the dial.  See that it is hilighted in RED.

The second image shows you what happens when the BVH is imported and you advance through the animation.  The leg just poke right through ignoring the dress altoghether.

When I import a BVH   - the dress doesn't move.  What is the difference?  The thigh is still translated as a result of the import but nevertheless it doesn't seem to work with the dress. 

Windows 10 - Poser Pro 2012 - 64Bit - 24GB RAM - 4 x 3.40 GHZ processor