Word comes from KERA-TV Channel 13 that Grapevine sibs Robert and Alexandra Switala will be featured Sunday at 12 noon on From the Top At Carnegie Hall . They'll perform "Passacaglia (After Handel)," arranged for violin and viola, by Johan Halvorsen. Allie's 14 and Robbie is 15. Allie previously was featured on From the Top at age 12, in 2006, when the program was recorded on the road at the Eisemann Center in Richardson. If you'd like a sneak preview of the Switala Duo performing, click here. ...