San Marcos Grill, a Mexican restaurant and bar in north Carson City, earlier this week began expanding in a project that included knocking out a wall and adding space to the east.The grill, located at 260 E. Winnie Lane in the neighborhood shopping center on the north side of the street and east of Carson Street, has been open in the current spot for about six years.Alvaro Brito, owner with his son, Marcos, showed a visitor the new space at mid-week. He said the restaurant was 3,800 square feet before the work, but would spread out another 1,800 square feet …