Hi James,
Greetings from Syncfusion support.
Query #: Multiple expand/collapse icon in multiple columns.
Unfortunately, we do not have support for “Multiple
expand/collapse icon in multiple columns” in our current architecture.
TreecolumnIndex property used to specifies the index of the column that needs
to have the expander button(which is not for showing Icons for multiple
columns)
Please refer to the API for TreeColumnIndex : https://help.syncfusion.com/cr/blazor/Syncfusion.Blazor.TreeGrid.SfTreeGrid-1.html#Syncfusion_Blazor_TreeGrid_SfTreeGrid_1_TreeColumnIndex
Regards,
Shek Mohammed Asiq