Hi andrea_r,
OK, I followed your suggestion that it's better to start with a new clean "empty" domain. So I created company.net for that purpose. I installed WPMU, no problem.
Now, please recall I have this:
company.com
companyblog.com
So I went to Admin>Blogs>Add Blog and "added" company.com. This created a new blog with the familiar "Hello world!" message, with the url of company.net/company. But this has nothing whatsoever to do with the real company.com site that actually exists on another server. I don't want users to manage their own blogs inside of company.net. I only want to connect to WP installs together under one roof.
So, at this point I don't get it.
In any case, shouldn't there now be a folder called "company" inside public_html? If there were, then would I need to migrate my entire actual company.com site into such a folder in order to make this work?
Meanwhile, I keep reading that domain mapping is the way to go, but when I try to use various plugins I find conflicting instructions/results. For example, the Yet Another Multi-Site Manager plugin gives back the error message "Sorry, domain mapping only works on virtual host installs." I found your reply to someone else who encountered this error, namely:
Right, this plugin only works if your blogs are in the format of subdomain.yoursite.com. If you have yoursite.com/blogname, then Donncha’s won’t work. Which is why you get that message.
you’ll need one specifically to work with subfolder/subdirectory setups, like the one we have here:
http://wpmututorials.com/simple-multi-site-plugin-e-book/
But yet you just suggested above that it's better to begin with a new fresh empty clean domain, which I did. Your error reply suggests it's better to use subdomains. Now I really don't get it.
My understanding was that WPMU using company.net as an umbrella would/could somehow "find" my company.com WP install and include it as one of its blogs, along with my other WP install, companyblog.com, all under one roof, for purposes of managing a membership that covers both sites (possibly using WishList, maybe along with BuddyPress).
Am I just not understanding something basic here? What? Please help. Thank you.