Symbolic link for a directory?

I’m interested in making a symbolic link for a directory, at least on the SD card like this:

A              C
  B  --link-->   B'

All directories, B is an ordinary sub directory of A, B' a child of C, but B' should be a symbolic link onto B with the same content but under another parent.

Has anyone made such a construction? How? Are apps able to use it?

Not good. Installed a terminal emulator now. Neither ln -s nor mount -o bind do work. Both fail with “permission denied”. I don’t want to root now. Bad.