This duet is entitled, "The Holiest Night." It is a medley of German Christmas carols that was arranged by Brent Jorgensen. (Click here to see the book that this music is in. It is filled with fantastic Christmas arrangements.)
Playing with my son is one of my favorite things to do in this entire world. It makes me happy. I hope that this song will bring happiness to your Sunday night and that you will enjoy this beautiful arrangement of the songs "Mary's Lullaby", "Still, Still, Still", and "Silent Night."