Here’s a screenshot of two/four square converging key search program. It has a grid for selecting which routes to use in the search. You could just choose all routes, but that makes the program take forever, especially in a tri-square key search where you are searching three keysquares.
The part of the display that took the longest to figure out was combining the giant size checkboxes in the grid with the ordinary sized 6×6 checkbox. That took a lot of searching through the web for information about html and css tags.