I discovered how to be more consistent after running into similar problems.  (i.e. FBMs for V4 wouldn't work at the "body level")

It's hidden in the daz3d notes about conforming for V4
http://www.daz3d.com/i.x/faq/0/-/?id=353

easiest way to make sure FBMs for all V4 clothing bind to the character  (or, what I do...)

1. always select the target character before loading a clothing item
2. use Set Figure Parent to parent the clothing item to the target character's BODY
3. Conform the clothing item as normal to the target character

voila - all FBMs work (at least if they are supported), although it is annoying that you can adjust them at all, unless you go to each part individually and compound your morph values.  but this works consistently for me.

hope this helps others..

Hope this helps others...