Hi Janet!
As the JR Kansai passes don't cover travel up to Kanazawa/Takayama, I think you'll be looking at the difference between a 7 day Japan Rail Pass or separate JR tickets. Lets take a look:
- Kansai airport > Kanazawa: ¥10150, (222mins, 324km)
- Takayama > Osaka: ¥10310, (220mins, 357km)
TOTAL: ¥20460 for 3 legs
To get to and from Shirakawa-go in your itinerary, you'll need to use the Nohi bus service which runs from Kanazawa through Shirakawago to Takayama. Please be aware that this bus is not operated by JR and so you will have to buy separate tickets. You can find timetable information on this bus at the [Nohi Bus online english timetable]
As the total JR charges for your route come to less than a 7 day rail pass (¥28,300) I don't think I can recommend for your party. You should aim to use basic JR tickets for your trip, and top up with local passes such as the Kansai Through Pass as needed.
The Kansai Through pass (Surutto Kansai) is a 2-3 day pass you can purchase for easy travel in the Kansai area including Osaka and Kyoto. The pass covers both metro, city buses and also local trains between cities, although you will be unable to use JR service. For more on the surutto Kansai, please see the official site.
Hope this helps!