Unit Overlap

I have two units that I teach at the same time, but how they overlap from year to year changes. I would like to be able to separate the units from each other so that I can adjust as needed. I would also like to be able to see the colors of each units days on the unit timeline without opening each day.
Currently each day is colored the same color even though they units are mixed together, and the units are hooked together. I can't move Unit B without extending or messing up Unit A.