The only players that can be edited are non-NIL players. On the "Exhibition roster you may get anywhere from 3-10 non-NIL players on a roster that are editable. So, there would be no way for you to mirror your Dynasty Roster with your Play Now roster. The best you could do with regards to editing is to sim about 6-7 years out in a Dynasty until all NIL players are gone from the roster, and then you'd be able to edit ratings. I don't think editing numbers are an option at all, nor is changing a players skin tone.