Ron: Your short answers will prevent others willing to explain me why and how to respond, because they will think I've got my answer. Although technically I did, That answer only works for others to think you offer good support and "you know your plugins/your stuff", ie. foreseeing the output, knowing all the answers for me… but if you put in my shoes, after my detailed plan and explanation, a single "NO" doesn't help me at all.
A single "domain mapping won't do what you're looking for"
Only gives me more questions which wastes my time more than actually testing the installation.
If you feel healthy and the doctor tells you "go home and write your last will" that DEFINITELY tells you how confident, smart and sure your doctor is but DEFINITELY won't help you at all.
I know you hate someone coming in here with a whole project to be build on others knowledge, but I do answer a lot of "if"s (sometimes I didn't understand correctly, sometimes people ask the wrong question and we can tell) and I like to explain why and how myself when I'm asked in a forum. I feel if I don't, I'd better don't reply. I want to help.
Domain mapping is the tip of the iceberg. Before that plugin maps the domains, I need other plugins for me to prepare the neccessary conditions for the folders/categories/subdomains/etc reflect what domain mapping needs in order to accomplish my goal.
Now, after investigating for 3 HOURS last night, and I found out a possible answer matching your useless 5 seconds answer. 10 seconds could have shorten my search 2 hours, that's helping out.
I found out domain mapping just mapps whole wp sub-installations to domains. I doesn't "listen" to folder estructures other plugins could make, and also the multisite installation doesn't provide a "main network" content area (posts). Content only comes from sub-sites, so I couldn't "add common posts".
I will research with a dummy sub-blog that will only provides the posts and common pages for the rest, and htaccess redirects to map the common pages (tagged pages) to new domains.
2 paragraph and up are welcome. Otherwise, let helpers do it. Even other who never developed a plugin can explain whys and hows.
I'll post the answer here to help others.