Create templated combo box columns, add cascading combo box editors to the templates, and configure the grid's cell edit functionality in inline mode.

Use CSS classes to enable or disable items in editors.

Create Two Cascading Combo Boxes for ASP.NET Web Forms

Сreate a combo box column's edit item template to bind the column to a filtered data source and configure the grid's cell edit functionality in batch mode.

Create a combo box editor and use its client-side functionality to specify the appearance of the editor's items.

Create a multi-column combo box editor and populate it with items on the client.

Get values stored in a hidden column of the Combo Box control on the client.