I need to display hierarchical data in a datagrid from the same table using linq. The first band to be displayed is the summary information and then the band under that are the lines that make up that summary information. If I create a .dbml file and a view with the summary information and the table i am using. I have created a relationship between the 2 and i do a linq query but the datagrid does not recognise it as hierarchical. Any pointers please?

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Dim SumMaterial As IEnumerable(Of vw_MaterialGrouped) = From mtsum In _Materials.vw_MaterialGroupeds _
                Join mt In _Materials.Materials _
                On mt.ProductID Equals mtsum.ProductID And mt.ItemID Equals mtsum.ItemID _
                Where mtsum.ItemID = _CurItem.ItemID Select mtsum