Geoffrey McDermott has developed a board where you can plug in up to 8 motor drivers to enable multiple power districts using the DCC++ Basestation.
Currently the only Internet source for this information is the DCC++ Facebook Page. You must be a member of Facebook and the DCC++ group to see it. Here is a link for those that are.
Facebook being what it is, it is difficult to link to the exact post. I suggest you go to the group, join, and search for the developer’s name. Geoffrey McDermott. He has made the documentation etc… available in a zip file that I will link below.