I should have known Obama was involved in some way.
The Museum of Science in Milan offers spectroscopic analysis of ivory (a small sample needs to be supplied) for 150 euros.
http://www.ivoryauthenticityandage.com/
Netsuke? How can such antiques currently be disallowed at auction?
Has your FIL considered Sotheby’s or Christies?
He might also do a little research on Japanese auction houses and go from there.
Really, what a mess - sorry your family is going through this.