I think the functionality on the PageSettings is fine, but you just made me realize a change we need in the Url Manager feature.

Early versions of mojoPortal did not have the friendly urls feature so all pages in the content system had urls like Default.aspx?pageid=x where x is the page id.

I later implemented the Url Manager along with support for friendly urls. On this feature you can specify a friendly url that maps to Default.apsx?pageid=x
Many versions after that I finally got around to integrating the friendly url with auto suggestion into PageSettings so a friendly url would be created easily when pages are created.

The problem I just noticed is that now because friendly urls are created right away, its not obvious what the pageid is so adding additional friendly urls is confusing in terms of what to put in the Maps To: textbox.

I think I need to change this to a dropdown list of the content pages to make it more usable.

As for the Url and use Url on PageSettings it has 2 uses, you can setup the main friendly url (which it  does for you by default or you can link to an external page on a different site if you enter a full url starting with http:// or https://
This allows external links in the menu.
Unchecking Use Url will make the page go back to using Default.aspx?pageid=x

I do take your point about it seeming to be designed for 1 friendly url per page but in fact that is the most common usage and I think it is good to have as simple as possible interface for common tasks like configuring new pages and let advanced users learn about url manager if they want additional friendly urls. In fact there is very few situations where you need to create a bunch of friendly urls and doing so could waste urls that might be useful later for other pages.

Of course now I have to fix Url Manager.