During this time, the sisters also played a small role in the formation of music’s next big thing — the Eagles. Frey was Joan’s boyfriend (“I’m pretty sure I wasn’t the only one,” Joan says of their fluid relationship), and had followed her from Detroit to L.A., staying at her apartment and hoping to break into the West Coast recording scene.
Naturally, Joan’s boyfriend was introduced to Alex’s husband, and Souther and Frey formed a band called Longbranch Pennywhistle. They released one album, with Joan’s inside cover drawings and a dedication to both sisters as their inspiration.
After that album didn’t take off, Frey soon created the Eagles with Don Henley, and Souther would be like an ex-facto member of the group, co-writing several of their hits, from “Best of My Love” to “New Kid In Town.” Would it have happened without the Sliwin sisters? Probably, but their part has been overlooked in histories of the band.