If you are accidentally stuck with combined morphs, say your character expression morph c is a combination of expression morph b that you want, and character morph a, dial morph c to 1.0 and morph a to -1.0. Difference is (a+b)-a=b is your expression morph. Result may not be exact (how 1.0 is your 1.0), but probably good enough to save the day.