Yep, here ya. Actually, if you could get a hand written, dated, signed and notorized document stating all the facts about the wood from your father-in-law, that would probably suffice as provenance if all the facts stated in the document can be verified e.g. names, places, people, his expertise in woodworking, etc. etc. IMO, I would personally try to make a guitar out of it, once I had the provenance to go with it. That might intriuge some good makers. Good luck and keep us posted!