[Plugin: Multisite Robots.txt Manager] multisite using directories

I’m using multisite with subdirectories, ie blog.example.com/foo and blog.example.com/bar. So I need a robots.txt file at the root blog.example.com that disallows not only Disallow: /wp- but that also Disallows /foo/wp- /bar/wp- etc.

Do you have any suggestions or examples for this kind of setup? I’m going with the following for now:

# robots.txt
User-agent: *
Disallow: /*?
Disallow: /wp-
Disallow: /feed/
Disallow: */feed/
Disallow: /cgi-bin/
Disallow: /comments/
Disallow: */comments/
Disallow: /trackback/
Disallow: */trackback/
Disallow: /wp-admin/
Disallow: /wp-content/
Disallow: /wp-includes/
Disallow: /wp-login.php
Disallow: /wp-content/cache/
Disallow: /wp-content/themes/
Disallow: /wp-content/plugins/
Disallow: /*/wp-admin/
Disallow: /*/wp-content/
Disallow: /*/wp-includes/
Disallow: /*/wp-login.php
Disallow: /*/wp-content/cache/
Disallow: /*/wp-content/themes/
Disallow: /*/wp-content/plugins/
Allow: /

Also, why do you include both the ‘wp-‘ line as well as the full directories?

http://wordpress.org/extend/plugins/multisite-robotstxt-manager/