Based on this thread https://theme.co/apex/forum/t/alternate-navigation-for-user-section-login-modal/45988/2 I just started using the Menu Item Visibility Control plugin https://wordpress.org/plugins/menu-items-visibility-control/ and Conditional Tags https://codex.wordpress.org/Conditional_Tags. Right away I see this working well.
Here’s my website: https://soniawilkinsonart.com
Here’s the coaching section that is currently hidden from the main site, the one I want to have a unique menu for: https://soniawilkinsonart.com/art-design-coach/
My ultimate goal is to change the menu when the person is in the coaching section. I don’t want to have to pay for the PRO theme to do this. I’m using the template tag for the visibility setting: is_page_template( template-artdesigncoach.php’ ). Note, this is a custom template I created just for the one section, and it’s saved under my x-child theme folder. I could use the category tags, but whatever. I’m here now, so thought I’d work with the templates.
My question (finally) is - what template file can I tag to cover all the other templates? like is_page_template( ‘global.php’ ) or is_page_template( ‘default.php’ ) ??
Or do I have to do an array of all the possible templates? is_page_template( array( template-blank-1.php, template-blank-2.php, template-blank-3.php, …) ) ???
Thanks for your help in advance!! 
Sonia
