I would add another column to your datasource (assuming that it is a Datatable). NOTE, i have never tried this on a datatable that already has data in it, I have only used this method when i needed to create a dynamic datatable.
dc = New DataColumn
dc.DataType = System.Type.GetType("System.String")
dc.ColumnName = "Whatever"
dc.ReadOnly = False
dc.Unique = False
This only adds the column to the datatable, you will have to loop through the rows of the datatable to add data to that column.
I will only tell you how to do it, not do it for you.
Unless, of course, you want to hire me to do work for you.
^^Thats my signature