Not sure if you meant this or not, so don't be offended; but just to clarify, I'm only talking about putting CB as FS, etc. in the depth chart, not actually changing the position. I know you can change the position from CB to FS, but can you keep the guy listed as a CB and still play him at FS via the depth chart?
Sounds like the answer is yes. I'm guessing the depth chart probably uses the same rule as the position change. In other words, if a guy can be changed to that position, he can be played at that position. Is that correct?