Staging A Performance
You can use the solo files to stage a performance, even if you do not have nine pianos or nine pianists. You will need a computer, some software (known as a Digital Audio Workstation - DAW), and some speakers.
Just download the parts you are missing from the links above, taking care to download the "full length" versions.
Once the downloads are complete, import the audio files into your DAW software - each DAW is slightly different, so follow the instructions for the one you have. Ensure that each imported audio file is exactly aligned with the others, so that they all start at the same time. Then when you click the Play button in your DAW, your pianists can play alongside.
If you are having trouble keeping in time, try downloading the click tracks, and also aligning them in your DAW - they work even better than a metronome.
If you are only missing one part, it is much easier to download one of the "Performance Minus One" audio files and play alongside that instead.
Of course, you can also use these performances for learning just your own part!