Hi Nalin,
Thanks for your interest in Syncfusion products.
By default, the dropdowngrid shows the grid content to which this celltype is embedded. To show different datasource in the dropdowngrid, you need to derive custom cell model and custom cell renderer from GridDropDownGridCellModel and GridDropDownGridCellRenderer classes respectively.
Please refer to the following sample that shows the custom grid embedded in the dropdown part.
http://websamples.syncfusion.com//samples/Grid.Windows/F79614.zipRegards,
Rajadurai
