Hi Sangyong Lee,
SfDataGrid currently doesn't have support to merge the column
headers. However, SfDataGrid supports showing multiple-column headers i.e.
Stacked Headers where you can show the merged multiple-column headers.
For more information related to Stacked Headers, please
refer to the below user guide documentation link,
UG Link: https://help.syncfusion.com/windowsforms/datagrid/columns#stacked-headers
Regards,
Dhanasekar M.
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