Create Multiple Subfolders in Lightroom or Have Lightroom Pick Up Multiple Empty Folders

Question

I currently have Lightroom organize files into subfolders by date when importing photos. So, for example, when returning from a shoot today, all images will be imported into a subfolder called "2013-12-18", which Lightroom will automatically created if it does not exist.
This is great.
Some of the images in the shoot belong to a set that I want to keep separate from the others. For example, an HDR or focus-stacked or panorama set.
What I do is create subfolders undernear the "2013-12-18" folder and manually move the sets into it. So I might end up with, for e.g.
  .../2013-12-18/
  .../2013-12/18/Set-01
  .../2013-12/18/Set-02
  .../2013-12/18/Set-03
  ... etc.
What I would like to do, however, is to reduce the pain of manually need to create each of the subfolders. Right now, I have to right click the parent folder ("2013-12-18"), select "Create folder inside 2013-12-18", type in "set-01", and repeat and repeat and repeat and repeat. This is very inefficient and tedious.
Now, I can easily write a Bash or Python script to automatically create as many subfolders as I need in the correct parent directory. But Lightroom does not show or recognize these empty subfolders until I go through the above process (i.e. pseudo-"create" the subfolders) OR go to "Library > New Folder" and ask Lightroom to add the new folder. I thought at first that the latter would be the solution (i.e., I could just go to "Library > New Folder" and add all the new, externally-created, empty subfolders. Unfortunately, this dialog only lets me add one folder at time.  Quelle douleur!!!
Any suggestions on how to go about doing this? A plugin or somehow record an action? Or maybe change the way I import?
Note that I do not mind actually moving the images belong to a set into each subfolder manually myself. In fact, I cannot imagine doing it any other way, as only I (and not Lightroom) can tell which images belong to a particular set. Yes, I know Lightroom can autostack by capture time, but that is not relevant here because (a) I am not stacking yet and (b) capture time between images in the same set can be highly variable. But I *would* like to automate or otherwise make more efficient the process of creating the subfolders or having Lightroom recognize my externally created empty subfolders.
Any advice would be greatly appreciated! Thanks!

Answer 1

Hi Christoph and all,
       So if there can only be one Public Root folder, I have a question about expanding EDMS to incorporate more uses.  We have a small group of users now who use it and so they already have the EDIPUBLICROOTFOLDER  document created with a certain doc type (FLD) which has some special rules coded with it that the lower level folders and documents inherit from it.   Now as part of our PLM project we are going to roll out EDMS to a broad audience who needs more general functionality which will come from an EDIPUBLICROOTFOLDER of a different document type (FOL).  Is it possible to create this new pubic root folder and somehow move the existing one with its specialized doc property inheritance to a subfolder within the new public root folder?
Thanks,
Joseph