I am trying to use domain aliases to point to subfolders on my site where the subfolders name would be hidden from resulting url on rewrite. domain-alias1.com and domain-alias2.com are domain aliases to domain.com

I have the following in my root:

domain.com/
   .htaccess (listed below)
  domain-alias1/
      main/
      .htaccess (contains only Options -Indexes)
   domain-alias2/
 ...

/.htaccess follows:

RewriteEngine on
RewriteBase /

RewriteCond %{HTTP_HOST} ^domain-alias1\.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^www\.domain-alias1\.com$ [NC]
RewriteCond %{REQUEST_URI} !^/domain-alias1
RewriteRule ^(.*)$ domain-alias1/$1 [L]

RewriteCond %{HTTP_HOST} ^domain-alias2\.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^www\.domain-alias2\.com$ [NC]
RewriteCond %{REQUEST_URI} !^/domain-alias2
RewriteRule ^(.*)$ domain-alias2/$1 [L]

domain-alias1.com (yields) -> Forbidden. You don't have permission to access /cogeco-gis/ on this server. (Which is what I want since .htaccess in domain.com/domain-alias1 contains Options -Indexes)

domain-alias1.com/test (yields) -> Not Found. The requested URL /domain-alias1/test was not found on this server. (Which is what I expect since test does not exist)

domain-alias1.com/main (yields) -> domain-alias1.com/domain-alias1/main/login_page.php

I am expecting rewrite to yield : domain-alias1.com/main/login_page.php where subfolder domain-alias1 is hidden from resulting url)

Any help on how to get expected results?