Error Pages Not Working

error pages i have added manually is not working because vbSEO create new .htaccess file

how can i run both of them ? (vbSEO and error pages) htacess is following

HTML Code:
# Comment the following line (add '#' at the beginning)
# to disable mod_rewrite functions.
# Please note: you still need to disable the hack in
# the vBSEO control panel to stop url rewrites.
RewriteEngine On

# Some servers require the Rewritebase directive to be
# enabled (remove '#' at the beginning to activate)
# Please note: when enabled, you must include the path
# to your root vB folder (i.e. RewriteBase /forums)
#RewriteBase /
RewriteRule ^((urllist|sitemap).*.(xml|txt)(.gz)?)$ vbseo_sitemap/vbseo_getsitemap.php?sitemap=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f
RewriteCond %{REQUEST_FILENAME} (admincp|modcp|clientscript|cpstyles|images)/
RewriteRule ^(.*)$ $1 [L]

RewriteCond %{QUERY_STRING} !vbseourl=
RewriteCond %{REQUEST_FILENAME} !chat
RewriteRule ^(.*.php)$ vbseo.php?vbseourl=$1&%{QUERY_STRING} [L]

RewriteRule ^$ vbseo.php?vbseourl=index.php [L]
RewriteRule ^(archive/.*)$ vbseo.php?vbseourl=$1&%{QUERY_STRING} [L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ vbseo.php?vbseourl=$1&%{QUERY_STRING} [L]