Importing question banks and applying locally-developed question formats

I hope my title says it all.  I can import existing Excel question banks into Storyline - no problem!  What i can't 'do' is apply either an existing Articulate question layout, or a locally designed question layout to the imported question slides.  The locally-designed question layouts are not part of the master slide layout - this is where i think (emphasis on "think") the question layouts need to be, but alas, I'm ignorant to this as well.