its not supported officially, but you can do this through REDitor, with licenses to open the draft class files and the MP filehttps://www.youtube.com/watch?v=buvXR1iJIRE
basically, after the season starts save and open the save in REDitor. Locate that year's generated rookies in the players tab, then copy paste in the players from the draft class save.
Its not the easiest thing to do since the columns dont line up properly iirc. But it is possible.