"chord" - a triad or seventh chord referred to by its roman numeral
"harmony" - functional sonority with a Roman numeral
"intermediate sonority" - an expansional device of some sort
"melodic embellishment" - instead of "melodic diminution"

I've mentioned the use of intermediate sonorities for expanding other chords, but seem to have arrived at a dilemma.  We agreed that it was distracting to label the middle sonority with a Roman numeral ("I____" is better than "I - V - I").  What I'm unsure about is how to explain the difference between diatonic and chromatic/applied intermediate sonorities without indicating the middle Roman numeral.  Any thoughts?

Also, do we want to set some kind of condition that requires the intermediate sonority to be triadic?  I'm afraid that if we keep explaining dissonances as "resultant intervals" we might run into this kind of thing:

CBC
GAG
EEE
CDC