Thompsons, Wainwrights and McGarrigles create musical worlds of their own, with the children following their parents’ footsteps, while also spurring the elders to expand their circle yet remain true to their past. Linda Thompson’s first album in six years opens with a song that she’d written for Rufus Wainwright. (Before she died, his mother Kate McGarrigle insisted that Linda finish it.) So Linda and ex-husband Richard, who adds a little guitar, perfected the song. Ron Sexsmith wrote the tune to Linda’s “If I Were a Bluebird” and Amy Helm added backing vocals, with Sam Amidon and David Mansfield backing her up. (Son Teddy also writes and performs.) One track is live from the legendary now-defunct Bottom Line club in NYC. Hardcore fans get what they need.