Not sure if you are referring to saving to subfolders or processing from subfolders.
SPA can already save to subfolders. If you use the CSV header SUBFOLDER, then it will automatically create that subfolder under the main save folder and save to that location. So for example, you could make subfolders for memory mate and individuals. Or you could make subfolders for 8×10, 5×7, etc. Just whatever you want.
Processing from subfolders from a CSV in more complicated so I never set that up. If 2 different subfolders have an image with the same filename then it creates a conflict. So for column A, it would have to be a path, not just a filename. Furthermore, the path structure would be different for Window and Mac. I see that being confusing for a lot of users. Plus, I would have to do a considerable amount of work to reprogram things in SPA. So I just haven’t really wanted to take on the project.