Hi Ken,
Thanks for posting your query to us.
You can set the multicolumn headers by declaring columnsets as mentioned in the code below:
$Columnsets>
$sfwg:GridColumnSetDescriptor Name="PersonalDataInfo">
$ColumnSpans>
$sfwg:GridColumnSpanDescriptor Range="R0C0:R0C1" Name="PersonalData">$/sfwg:GridColumnSpanDescriptor>
$sfwg:GridColumnSpanDescriptor Range="R1C0" Name="Name">$/sfwg:GridColumnSpanDescriptor>
$sfwg:GridColumnSpanDescriptor Range="R1C1" Name="BirthDate">$/sfwg:GridColumnSpanDescriptor>
$/ColumnSpans>
$/sfwg:GridColumnSetDescriptor>
$/Columnsets>
Also,Please refer the below link for details about the issue:
http://www2.syncfusion.com/ug_62/gridweb/ColumnSet.htmlPlease let me know if you have any other questions.
Regards,
Janagan