Review of Angels Sing

I watched this last year for the first time and kept it on my DVR since! I LOVED all the music - but it wasn't overly musical. My only question is who the singer is with Lyle Lovett when they are singing at his characters house!? I know I've seen her somewhere before and I'm pretty sure she was a famous singer from the 70's. If anyone can answer this question for me, I'd sure appreciate it! I think what makes it so fabulous is that it could be done any time of year, it just happens to be one of Christmas. It's wonderfully family, friends and relationships. In viewing this, it reminded me of the strain of relationships in families but all can be avoided if everyone is willing to talk! I didn't really view it as a religious movie.