This reminds me, surely it's Bernie playing the mandolin on this tour during Saturday Night. Or is it pre-recorded? You can definitely hear it. Have they ever mentioned anything about it at all at the live shows? You would think they would.
I don't know (though I've never been to an Eagles gig, let alone one on the HOTE tour ) but it could equally be Steuart Smith I suppose. He seems to be able to play anything with strings and goes absolutely non-stop.