Basically, the way to modify the values to be exported is subscribing for the ElementExporting event of RadGridView and setting the value to be exported (e.Value) as you wish.
sender, GridViewElementExportingEventArgs e)
(e.Element == ExportElement.HeaderCell)
var column = e.Context
"any value you wish to export"
If you would like to export an additional row, then you can subscribe for ElementExported event. This is also illustrated on our online demo on Exporting RowDetails
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