1. The Seller's insurance is liable up until settlement. If it's that important to you, ask them to submit a claim. Make sure that claim will not be affected if owner sells house before decision and payout.
2. If you don't want to postpone closing, get proof that the claim has been submitted and agree on a replacement value with the Seller. Set that amount aside in escrow (with the title company) to ensure that the Seller is motivated to pursue the claim. If the insurance company denies, you may be able to have these funds redirected to a vendor to replace these items. You, however, cannot receive the funds. Document it in writing exactly what happens to these funds should the insurance company not approve claim.
3. Agree on a credit with the Seller. You usually cannot walk away with funds, so this may involve decreasing the sale price. If you and the Seller decide/agree on this option, you should do this NOW as settlement is fast approaching.
4. You say they are valuable, but if it is not a historic mansion and simply an older home, you can choose to accept the home as-is (you can still try to get a reduction in sale price as mentioned in item 3 above) and have the "fun" and adventure of finding replacement items online or from architectural salvage stores (there's a great one in Philly). This way you can "add" to the story of the home and add your own touch.
Hope this helps and good luck to you!
Eric Axelson, Associate Broker
Licensed in NJ and PA
Kurfiss Sotheby's International Realty