merging of cells in table

Is it possible to merge cells in table and add a component in that merged cell.

For example:
I want to add a table component in row of a table.
Is it possible to do this.

Merging cells is not possible, but adding components to cells is. If you really want, you can add a Table inside a cell but rendering a Table inside a Table gets very slow easily.

Is it possible to add html layout for adding row to table?