The level 1 links in your navigation tree are required to be the landing page created with the "Index Campus" template, and the menu structure underneath will be the navigation setup for each campus. The only exception is for the first level 1 link, which is "Network".  The "Network" link is going to be your default non-campus home page, and all child links that are not campus specific will live under this level 1.

The system does not allow duplicate pages.  If you need the same page for all campuses a good rule of thumb is to name your page with the campus in the title re. "About Us - Bellingham" and then use the Header Text field to place the Page Title and any additional text needed (Sub Title, etc.).

Since each campus will have its own landing page for sermons, etc. you SHOULD NOT use the select menu option "System Default For:" when assigning module pages in the navigation. You can leave that dropdown blank.