Hi Lucas,
You can add multiple sitemap files by adding custom entries to your
web.config file.
After a user has logged on you will presumably have a method for determining
what content to now load. For example, you could use a set of master pages
to display the required menu/mappath/treeview control with the sitemap
definition to use for that person/account type.
The master pages can be nested so that you retain a common theme from a
global master page (used on all pages, regardless of user) and the
sub-master using the appropriate sitemap.
I use a similar system (without logons) for my company site at
www.copeohs.com. What I do here is maintain a "full" sitemap file for the
breadcrumb (sitemappath control) and separate sitemap files for the vertical
side menu. Each section that requires a different side menu has a nested
master page that inherits from a global root masterpage.
The root masterpage applies the header banner and top menu and breadcrumb,
plus placeholders for cascaded use by the nested masterpages. (I also add
placeholders for javascript and meta tags).
So for a fairly large site I only have a handful of masterpages and
corresponding sitemap files.
Hope that provides some inspiration!
Al