.htaccess - override apache rewrite rules with htaccess

working on a server that hosts multiple
domains.
Somewhere in apache config is a rewrite rule that is set for ALL
domains.

What happens is if a user
goes to example.com/foo they are supposed to get redirected to
example.com/foo_bar

However, in one domain, I
want to override this behavior so that the url stays at example.com/foo and does not
redirect. I've been searching and trying various rules and conditions to no avail. I
don't have access to the apache config, but I am using .htaccess for some rewrite rules
on this domain.

here's my rewrite rules in
.htaccess:

            mod_rewrite.c>
 RewriteEngine on

 # this isn't
            working

 # RewriteRule ^(foo)($|/) - [L]


            RewriteBase /

 RewriteCond %{REQUEST_FILENAME} !-d

            RewriteCond %{REQUEST_FILENAME} !-f
 RewriteRule ^(.*)$
            index.php?/$1

 # this didn't work either
 # RewriteRule
            ^/foo index.php?/$1
            [L]