.htaccess to provide 'flattened' search engine friendly CMS URLs - mod-rewrite

Question

I am using CMSMADESIMPLE for a website. It can generate search engine friendly URLs using a .htaccess file and mod_rewrite.
BUT it is possible to insert anything between the base url and the requested page. For example all these URLs will work:
www.example.com/aboutus
www.example.com/home/aboutus
www.example.com/any/rubbish/i/enter/aboutus
I have seen other sites using Wordpress where it is possible to enter the same in the address window, but it will redirect back to the lowest level i.e. www.example.com/aboutus. I would like to achieve the same thing but cannot master .htaccess to do it.
The relevant bits of the .htaccess file are:
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ index.php?page=$1 [QSA]
</IfModule>
I am assuming that this is something that can be achieved just using mod_rewrite and doesn't require changes to the PHP code within the CMS.
If that's not possible I would like to setup a permanent redirect from some URLs within the CMS which have been indexed by Google.
i.e From www.example.com/home/aboutus to www.example.com/aboutus
I tried adding a RewriteRule to .htaccess without success:
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteRule home/aboutus aboutus [R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ index.php?page=$1 [QSA]
</IfModule>
Any help appreciated.

Answer 1

Look at the sample htaccess.txt file in the doc folder. There is a section about parent child.
# Rewrites urls in the form of /parent/child/
# but only rewrites if the requested URL is not a file or directory
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ index.php?page=$1 [QSA]