The introduction

 In the previous example we have drawn a table with cell merge via component «Resizable pattern» - this approach quite flexible, but requires building the extensive form structure. 

However, for such a trivial task like this, we able to use another component - «Grid» , that provides very simple insertion of ordinary table into the Excel-form. In addition, this component supports automatic cell merging in accordance with the structure of the context (ie, hierarchy levels, formed by the combination of nested tables):