Symlink one directory, its contents and file structure to target directory, with automatic updates

Question

Asked something similar a while ago in Unix&Linux but got yelled at, so will try again...

Let me take a directory called DIR with the structure

DIR/
|----> file1.txt
|----> file2.txt
|----> file3.txt
|----> SUB_DIR/
         |-----> file4.txt

What I want to do is create another directory whose contents would be symbolic links to the files and directories in DIR. That is, denoting symlinks by ** name **

LINKED_DIR/
|----> **file1.txt**
|----> **file2.txt**
|----> **file3.txt**
|----> **SUB_DIR**/
         |-----> **file4.txt**

From previous suggestions, I've been able to do this via GNU Stow:

stow DIR -t LINKED_DIR

what happens is that file_{1,2,3}.txt in LINKED_DIR are turned into symlinks to the corresponding file in DIR, and SUB_DIR appears as a symlink to the corresponding directory in DIR, but the files inside are not symlinks:

LINKED_DIR/
|----> **file1.txt**
|----> **file2.txt**
|----> **file3.txt**
|----> **SUB_DIR**

$ls LINKED_DIR/**SUB_DIR**
file4.txt

What I would further like to do is make sure that when a file is added to DIR/, the mirror directory LINKED_DIR/ updates with a symbolic link to the new file. This does not work with the setup as described, e.g. creating DIR/file5.txt does not lead to the symlink DIR/**file5.txt**, and creating DIR/SUB_DIR/file6.txt leads to a copy/the same file (not a symlink) appearing in LINKED_DIR/**SUB_DIR**

Has anyone found a solution to this? I'd like to replicate the relationship between /usr/bin and bin, where the contents in bin are linked to the contents in /usr/bin, and changes (e.g. the addition of new files) are automatically reflected.