When ABC relaunches its ratings-challenged gem, Karen Sisco, in March, Carla Gugino's U.S. Marshal will mix a little pleasure with her business. "There will be a romantic story [involving] someone from her past," reports exec producer Bob Brush, who also plans to "set up more conflict between Karen and her dad (Robert Forster)... [all] to put her through some emotional journeys." ABC is sending Sisco on a trip as well: The network is expected move the show to Sunday nights, where it will be paired with fellow tough-chick drama Alias. Predicts Brush: "[They'll] be great together."