Maintenance redirect and rules

Hello. Please help

I want to redirect users but me to a maintenance page momentanly.
I have the following in my .htaccess

Options +FollowSymlinks
RewriteEngine on

RewriteCond %{REQUEST_URI} !/maintenance.html$

# here filter the developer's IP/
RewriteCond %{REMOTE_HOST} !^xx\.xx\.xx\.xx

RewriteRule $ /maintenance.html [R=302,L]

So, now I install the multisite WP, and need to add the .htaccess like this:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule  ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule  ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

How can I combine this rules in order to keep my temporary redirect?

I will comment extra rules after my site will be OK.