Implement tree structure for shared folders (or shared subfolders)

[wnhrt]

Is your feature request related to a problem? Please describe.
I have groups of shared folders that should always stay on the same drive.
For example, I have several shares that are used by SMB. I back up all shares via rsync.

/SHARES      <-- /SHARES (rsync)
  /SHARE1    <-- /SHARES/SHARE1 (SMB)
  /SHARE2    <-- /SHARES/SHARE2 (SMB)

In the event of a drive failure or replacement, I have to adjust each shared folder individually.

If subfolders would take over the configuration of the file system from the root folder, all folders in a group can be moved with five clicks. In addition, complex folder structures can be displayed more clearly in this way.

Describe the solution you'd like
An option to create shared subfolders, which are created inside the parent and take over their file system configuration.
Here are sketches of what this could look like

This should preferably be possible over several depths, e.g.:

/ROOT
  /SUB1      <-- /ROOT/SUB1
    /SUB3    <-- /ROOT/SUB1/SUB3
  /SUB2      <-- /ROOT/SUB2

Describe alternatives you've considered
//

Additional context
It might be helpful for users to point out that snapshots with btrfs are not recursive: https://btrfs.readthedocs.io/en/latest/Subvolumes.html#nested-subvolumes
(I assume that shared folders are subvolumes because they are individually capable of creating snapshots)

How ACLs can/should be handled is another point to consider.