Siblings can be savage like that - especially the older ones! My (much older) sister saw Led Zep, Slade and my brother in law saw The Beatles regularly atThe Cavern, and he hated them - we never agreed about music!
Yes, I went to a Scotland rugby game at Murrayfield some years ago, giving up a ticket to see Jeff Buckley in London that week-end. I thought that I’d see him ‘next time’, but (tragically) he never made it back to London.
Miles Davis, Feb 1st 1975 - the afternoon set at the Osaka Festival Hall that became the album Pangaea and also the evening set that became the album Agharta.
Paul Bley, Gary Peacock & Paul Motian - the March 1999 gig at the Aula Magna di Trevano in Switzerland that became the album When Will The Blues Leave.
Keith Jarrett, Gary Peacock and Jack deJohnette - the July 2000 gig at the Royal Festival Hall in the Southbank Centre that became the album Inside Out.
Black Flag, all lineups but in particular in 1984 with Ginn, Rollins, Kira, Stevenson (link)
(saw Rollins Band, the one Black Flag reunion with Greg Ginn and the other with Morris, Stevenson and others, but never the real BF)