Last children

I'm not sure how to title this or if it's a duplicate of previous posts, but just in case somebody can point me in the right direction:

I have a site with a "Primary Links" menu that looks like this:

• News
  • department news
  • alumni news
  • events
• About
  • our program
  • faculty
  • students
  • facilities
• Resources
  • for studetns
  • for alumni

I am displaying the first-level links inline in the header ( News | About | Resrouces ) and the secon level links (the children) are displayed in the sidebar. I use Menu Trim to display only the links for the section you're in. So if you click on "Resoruces" in the header, the sidebar shows only "for students" and "for alumni" links, not everything.
Now, this works great for pages but not for my stories. I've configured "Events" section for example to be a collection of stories with a keyword "events" applied to node's taxonomy. So if I click on "Events", I don't get a specific node, I just get a listing of 10 most recent nodes that belong there. When I click on one of the nodes listed there, it takes me to that node, but the sidebar menu disappears completely then!
Is there any way I can make the side menu stay on that last node based on the keyword? For example if a node has a any type of keyword, show the menu under "News"? Is my description at all intelligible? Am I replicating what's been discussed or is this somehow different because I'm using taxonomy to section things?