navigation highlighting indicator

hello

My client wants to consolidate the left navigation in their course, so they've renamed many items to be the same heading. (Using SL3)

In doing so, they want to remove duplicates from the navigation, and simply leave the heading highlighted that it pertains to, as opposed to the actual slide a user is on.

For example, in the image below, they want all duplicates removed and each topic only listed once. I realize I can remove items from the nav, but then that item is no longer highlighted as the user moves through the course, which I think is a bad user experience. 

My client expects that the program can continually keep the topic item highlighted. I tried to explain that each item is related to a specific slide in the course but they are still asking for "Specimen Triage..." to be highlighted, even as the user has moved on to slide 2.9 (and I've removed 2.9 from the navigation since it's a duplicate...)

Is there a way to handle what they are asking for??

Thanks!

Karen