I'm not actually sure this is quite the right way to approach this problem, so if I'm just off in the wrong direction, please help me figure out where I should be heading.
I have a collection of several hundred geolocated items, each of which is tagged with one or more attributes. I want to save the items as a KML/KMZ file such that it's trivial for a Google Earth user to show/hide the items based on their tags. Right now, I've just got a folder for each tag, and the items duplicated between folders, so there might be three copies of one item across three different folders. This works great if the user only wants to look at one tag at a time -- just select that folder and deselect the others. However, of course, if you've got 2+ folders selected, you wind up with duplicates of the same item showing up on the map.
Is it possible to have a single placemark which is "symlinked" into more than one folder, such that if it's in two folders and both are enabled, only one copy of the placemark will actually appear on the map?
If not, is there some other useful mechanism within the KML/KMZ format that will give me the sort of functionality I'm looking for?