How to handle multiple host names?

Let us assume:
Installed and functioning multisite (sub-domain, dedicated IP).
Domain abcd.com
Several sites like
test.abcd.com, anothersite.abcd.com, properweb.abcd.com etc

Installed domain mapping and mapped new domain anothersite.com (and also host http://www.anothersite.com) to site anothersite.abcd.com. Works perfectly!

Now I need to map a second domain (newdomain.com with accompanying www host) to the same anothersite.abcd.com.

How do I add a second mapping?

I presume I could get it to work by adding entry manually in mySql db, but how do I set which of the two mappings should be the default mapping?

(is it possible that the plugin can handle multiple mapping after fiddling with line 31 of plugin PHP-file ?).

I would like to be able to amend/change behavior of plugin to the following use cases (all mentioned domains/hosts point to the appropriate multisite abcd.com IP of course):

1. If user enters http://anothersite.com (or http://www.anothersite.com) the site present at anothersite.abcd.com is presented, but address bar shows http://anothersite.com.

If user enters http://newdomain.com (or http://www.newdomain.com) the site present at anothersite.abcd.com is presented, and the address bar is changed (in effect a redirect) to show http://anothersite.com.

2. If user enters http://anothersite.com (or http://www.anothersite.com) the site present at anothersite.abcd.com is presented, and the address bar is changed (in effect a redirect) to show http://newdomain.com.

If user enters http://newdomain.com (or http://www.newdomain.com) the site present at anothersite.abcd.com is presented, and the address bar text still shows http://anothersite.com.

And of course a third, fourth etc domain could be mapped and a single domain could be set to "default" causing automatic redirect.

Furthermore a preference setting would be excellent to allow NO default domain to be in effect. That is whatever mapped domain I enter remains in the client address bar.

I know this is most probably an extension of the functionality of the plugin but the domain mapping plugin present at Wordpress.org seems to have some of the desired features (multiple mappings, I believe).
I love this plugin though, it seems very stable and less prone to interfere with other plugins etc.
Greatful for any comments! Thanks