If you have a KML or KMZ file that has multiple shapes within it, and you'd like to use these shapes for creating things like segments or a project location, use the following approach to break the individual shapes into distinct KML or KMZ files.
Step 1: Install Google Earth Pro on your computer
Step 2: Open your file in Google Earth
You can drag the file into Google Earth or use File -> Open.
Step 3: Right click each shape and "Save Place As"
Using the dropdown list in the "Places" tab on the left, or by right clicking each shape, click the "Save Place As" option to save a new KML or KMZ file.
Once your files are saved locally, you can upload each KML or KMZ to PublicInput for use in common tools like Segments and Boundary Shapes for maps.