Vba trial and errror

Hi I have a rota in excel with users doing different shift see attached doc. I then have an error column R. What I'd like the vba to do is keep moving each person found in D5 TO Q40 to different boxes until no error are found in column R (which will have a number in to represent the number of errors in that row) or if not find the minimum amount of errors. One other thing if I highlight a box in red yellow or black I don't want that user to be moved.



Cheers