Hi Devin,
Thanks for your interests in Syncfusion Products.
Please refer to the following forum thread that deals with relating two comboboxtype columns in griddataboundgrid.
http://www.syncfusion.com/support/forums/grid-windows/36755Here is the modified link for the sample provided in that forum thread.
http://files.syncfusion.com/support/samples/Grid.Windows/7.3.0.20/RelationInComboBox.zipRegards,
Rajadurai