My Gal Loves Music (1944)

A non-sister sister act, Judy Mason (Grace McDonald) and Peggy Quinn (Betty Kean), is stranded in a tank-town, and thanks to a brainstorm by Dr. Bilbo (Walter Catlett), the local patent-medicine pusher, are entered in a child-talent contest. They win the grand prize of a trip to New York City to appear on the radio program starring Mel Morgan (Bob Crosby) and sponsored by vitamin manufacturer Rodyey Spoonyer (Alan Mobray).