Protected Sub parentRepeater_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) 
                               Handles parentRepeater.ItemCreated

        If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem Then
            Dim ch As Repeater = CType(e.Item.FindControl("childRepeater"), Repeater)

            AddHandler ch.ItemDataBound, New RepeaterCommandEventHandler(AddressOf parentRepeater_ItemDataBound)

        End If

    End Sub


    ' на это событие подписываем
    Protected Sub ChildRepeater_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs)

        Dim item As RepeaterItem = e.Item
        If item.ItemType = ListItemType.Item Or item.ItemType = ListItemType.AlternatingItem Then
            Dim grid As BookInfo = CType(item.FindControl("BookInfo1"), BookInfo)
            grid.SetValues(e.Item.DataItem("BookURL").ToString, e.Item.DataItem("BookName").ToString, Now(), "", "", 0, "", "")
        End If

    End Sub

<asp:Repeater ID="childRepeater" runat="server" DataSource='<%# Container.DataItem.Row.GetChildRows("myrelation") %>' OnItemDataBound="ChildRepeater_ItemDataBound" >