One other question on this one:
 
We often have a BOM where we make one item, but a second product is created that is incidental to making the first one.
 
We used to account for this by including the incidental item as a negative on the BOM, so during backflush it would be added to stock.  
 
It seems that with the new B setting, this can no longer be done.  Is this a possibility to change?  Otherwise, the "B" setting is perfect.