Hi Elias,
Thank you for your interest in Syncfusion products.
A bounded column has it own datastore to store the values entered in it. But in an unbound column there is no datastore present in it, so it has to be handled manually by adding any collection like hashtable. To make unbound column work together with sort, assign key as corresponding primary key value in the row in the Key/Value pair of the external collection.
Refer the sampel from below link, it shows the behavior of unbound column in GridDataBoundGrid.
http://websamples.syncfusion.com/samples/KB/Grid.Windows/UnboundCheckboxColumn/main.htmPlease let me know if you have any queries.
Regards,
Lingaraj S.