If you copied the Excel cell values into iGrid using the LoadFromArray method or manually by setting the CellValue properties, iGrid knows nothing about relations between your worksheet cells coded with formulas. The easiest way to update iGrid in this case, sure, is to reload it fully. This may work good for small grids, but for huge grids you may need to do a more intelligent uploading and copy only the changed cells to avoid any performance issues. You know what formulas and where you are using, and this will allow you to implement such an algorithm.