.htaccess Multiple subdirectory rewriting to www-root - .htaccess

Question

I have the following folder structure:
www-root
Backend
Config
Etc
Frontend
Administration
StoreFront
I would like to be able to access the directories from the main url and hiding the subdirectories in between.
So the administrative part I should be able to access like this:
http://localhost/Administration/
The main page which is stored in the subdirectory "StoreFront", I want to be able to access from the root:
http://localhost
This is the code in my .htaccess file so far:
# Store Redirect
RewriteEngine on
RewriteCond %{HTTP_HOST} ^localhost [NC]
RewriteCond %{REQUEST_URI} !^/Frontend/StoreFront
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /Frontend/StoreFront/$1
RewriteCond %{HTTP_HOST} ^localhost [NC]
RewriteRule ^(/)?$ /Frontend/StoreFront/index.php [L]
RewriteCond %{REQUEST_URI} !^/Administration
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /Frontend/Administration/$2
This code however does not work correctly. It rewrites every file except the index.php file to the Administration subdirectory. One side note: php files which are in the backend directory should remain "includable" from the frontend.

Answer 1

Let me tell upfront you that what you're trying to achieve is mission impossible, now let me tell you why. You have this rule:
RewriteRule ^(.*)$ /Frontend/StoreFront/$1
and down further you have:
RewriteRule ^(.*)$ /Frontend/Administration/$2
You cannot have .* going to both the places. You need to distinguish these 2 paths somehow.
It is besides the point that you have other problems also e.g.:
Not using L (LAST) flag wherever needed
Using $2 instead of $1 in 2nd rule
EDIT: Based on your comments:
Options +FollowSymLinks -MultiViews
# Turn mod_rewrite on
RewriteEngine On
RewriteBase /
RewriteRule ^(Administration(?:/.*|))$ /Frontend/$1 [L,NC]
RewriteCond %{HTTP_HOST} ^localhost [NC]
RewriteRule ^$ /Frontend/StoreFront/index.php [L]
RewriteCond %{HTTP_HOST} ^localhost [NC]
RewriteCond %{REQUEST_URI} !^/Frontend/StoreFront
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /Frontend/StoreFront/$1 [L]