Loosely based on Kathryn Forbes' book -Mama's Bank Account-, this film actually contains richer detail and more intricate character- izations. In turn-of-the-century San Francisco, young Katrina Hansen chronicles episodes of life with her extended family, who combine traditional Norwegian values with "modern" American ways. So successful that it became a popular radio show, and then a TV sitcom, both with Barbara BelGeddes and Irene Dunne from the film.…