PPF means Pack Profile File, which is to be imported to YEM (version 2.5 for Genos) so we can select all or a portion of the voices and styles contained in the Expansion Pack inside YEM. Expansion packs in the form of PPF is flexible.
PPI means Pack Installation File, which is the file created by YEM, to be stored on a USB flash drive, to be installed on appropriate Yamaha arranger keyboards. Expansion packs in the form of PPI is inflexible and meant not to be altered.
If what you got is a PPI file, you should just install it on your Genos: Menu - Menu2 - Expansion - Pack Installation, then select the name of the PPI file on your USB1 to install the expansion pack. There is nothing for YEM to process PPI file since the file is already the final installation file.
Since the Expansion flash area will always be reformatted whenever you install a new PPI file, all of your currently installed Expansion packs on your Genos will be wiped. You simply cannot incrementally install additional expansion packs on top of the installed expansion packs. If you still have all the PPF files imported in your YEM, then your can always re-create your original "Genos_PackInstallData.ppi" file. Your original "Genos_PackInstallData.ppi" may still be on your USB1 stick, so you can just re-install it after you are done with your new pack.
Thanks,
Paul