On the "Use External Binary Morph Targets" I just leave this always unchecked which is the best way to go, which is also what most others to since it is not a problem with being able to read a file with V4 in it. But as kuroyume has stated. Now on to your original question.

I have noticed that sometimes when I save a V4 morph that I created and just copy over to the Figure or Pose folders sometimes the body morphs dials go back to 0 but actually retain the morph, its strange sometimes when I do saves and want to compare things. I keep the original and bring in a new figure that either has the changes already applied (figure folder) or apply them (pose folder) to see if everything worked since Poser 7 has some glitches still :tongue2: . I never thought about trying to see if this happens in Poser 6 until now with your question.

One thing I am starting to do now which I have not noticed yet is saving the morphs as a Full Body Morph, try that after you made all your alterations and see if that gives you any better help.