While it may not be fashionable to float new ideas about using MSFT's sunsetted mapping programs , I thought I might share this little trick that occurred to me for those who might still care.
Suppose you have multiple map files that you want to be able to access quickly from a master map. This could be a sales or service person with a geographic territory that has multiple routes within that territory that need to be accessed as the user requires. Or it could be an extensive multi-day cross country route with possible sub-alternative routes.
The answer is pushpins set up with hyperlinks. The way it would work would be to have all the sub-routes in a single folder (or at least one folder for each pushpin set). Set up the hyperlink properties to point the pushpins to that folder. For instance, if the sub-routes are in a folder called "c:\maps\texas\" you would select "Have Streets and Trips automatically create a set of hyperlinks" in the pushpin set properties and type in "//c:/maps/texas/*.est" in the entry box.
Now, the pushpins in that particular set will automatically open the map files in the target folder that correspond to those respective pushpin names if they are clicked with the control key held down. It takes a few seconds and the sub-files will open behind the master map so you will not see them right away and not at all it the master map is "maximized." You can save some aggro if you minimize the master map immediately so that the newly-opened sub-file appears immediately. If a sub-file is already open, you will get the appropriate pop-up warning box that you might not see but it is there. You can alt-tab through the open files to access them as needed.
One small caution: I find that the hyperlink function will not hand file names that have one or spaces in them. Although the hyperlink box will insert "%20%" in an attempt to make it acceptable to Windows, it will not pull up the linked file. Therefore, both the file and the pushpin names have to be without spaces for this to work. This seems to apply to any sort of linked file such as *.pdfs, fwiw.
I hope someone else finds this helpful.