since it looks like metamorphosis is not defined as a "stance" i cant think of a way to make rdx auto-swap the bars, at last not with the options currently available
on the other hand, i dont really see the need for a bar-swap, since the only thing you use only when in demon-form is immolation aura and eventualy demon charge, and for just one or two buttons i wont need a complete new bar `?
for the bql encounter (and other stuff, f.ex. the cannons on gunship-battle and vehicles in general) you have to define a state "[bonusbar:5] possess"