Merging sheets creates conflict when images exists on both sheets

Hi

I have a solution of creating and merging Excel-files in a webservice.

This has been working fine, until both of the Excel-files began to contain images.

As an example, the service recieves one Excel template and one Excel workbook.
The goal is to create a new Excel workbook consisting of the supplied parts.

Since the template is indeed a template (xltx), I start of by working with the workbook.
I then merge all worksheets from the template file to the workbook file.
This is done in memory with the help of EPPlus version 3.1.2 and the following routine where grmName is path to the template file and wbkName is path to the workbook:

Friend Sub XLAddInfoSheets(ByVal grmName As String, ByVal wbkName As String)

        Dim targetFI As New FileInfo(wbkName)
        Dim templateFile As String = grmName
        Dim ContentOverrides As New ArrayList

        Try
            Using t As New ExcelPackage
                Using Tstream As New FileStream(wbkName, FileMode.Open, FileAccess.ReadWrite)
                    t.Load(Tstream)
                End Using
                Using d As New ExcelPackage
                    Using Dstream As New FileStream(templateFile, FileMode.Open)
                        d.Load(Dstream)
                    End Using
                    For Each dws In d.Workbook.Worksheets
                        Dim addOK As Boolean = True
                        If dws.Name = "Försättsblad" Or dws.Name = "Cover Page" Then
                            Dim tmpName As String = dws.Name
                            For Each twx In t.Workbook.Worksheets
                                If LCase(twx.Name) = LCase(tmpName) Then
                                    addOK = False
                                    Exit For
                                End If
                            Next
                            If addOK Then
                                t.Workbook.Worksheets.Add(tmpName, dws)
                                t.Workbook.Worksheets(tmpName).Hidden = dws.Hidden
                            End If
                        End If
                    Next
                End Using

                t.SaveAs(targetFI)
            End Using
        Catch ex As Exception
            WriteLogg("Could not merge coverpages from the template.", ex.Message, logFile)
            Exit Sub
        End Try

    End Sub

When opening the created file (if both the template and the workbook contains images) shows a repairable error.
After the repair is made, the images in the inserted sheets is actually an image from the original workbook, not the same image as in the template sheet.
I realise that there is a mixup of relations causing this, so I tried looping through the images in the inserted sheets and delete the original image (DrawingPart) and add the image again.

This is done with the following code where wbPart is the actual Workbookpart and imagePath is path to the image which is extracted to disk earlier:

    Private Sub XLRelateImages(ByVal wbPart As WorksheetPart, ByVal imagePath As String)

        Try
            Dim drawingPart = wbPart.DrawingsPart
            If drawingPart IsNot Nothing Then
                Dim doc As New XmlDocument()
                doc.Load(drawingPart.GetStream())
                Dim ns As New XmlNamespaceManager(doc.NameTable)
                ns.AddNamespace("a", "http://schemas.openxmlformats.org/drawingml/2006/main")
                ns.AddNamespace("xdr", "http://schemas.openxmlformats.org/drawingml/2006/spreadsheetDrawing")
                Dim list As XmlNodeList = doc.SelectNodes("/xdr:wsDr/xdr:twoCellAnchor/xdr:pic/xdr:blipFill/a:blip", ns)
                Dim pairList As New List(Of KeyValuePair(Of String, String))()
                For Each node As XmlNode In list
                    For Each attribute As XmlAttribute In node.Attributes
                        Dim pair As New KeyValuePair(Of String, String)(attribute.Value, attribute.Name)
                        pairList.Add(pair)
                    Next
                Next
                For Each image As KeyValuePair(Of String, String) In pairList
                    Dim id As String = image.Key
                    Dim name As String = image.Value
                    Dim oldPart As OpenXmlPart = Nothing
                    If name = "r:embed" Then
                        ' get ImagePart via id
                        oldPart = drawingPart.GetPartById(id)
                        ' delete ImagePart
                        drawingPart.DeletePart(oldPart)
                        ' add the ImagePart
                        Dim newPart As ImagePart = drawingPart.AddImagePart(ImagePartType.Png, id)
                        ' replace image
                        Dim replacement As String = imagePath
                        Using stream As New FileStream(replacement, FileMode.Open)
                            ' feed data to the newPart
                            newPart.FeedData(stream)
                        End Using
                    End If
                Next
                ' save xml document to the stream
                doc.Save(drawingPart.GetStream(FileMode.Create))
            End If
        Catch ex As Exception

        End Try

    End Sub

When I examine the result of this I still get the same error when I'm opening the file, but the correct image is now shown on the inserted sheets.

I believe there must be some other relation that is left in the workbook, but I have not been able to locate it.

Can someone help with sample code in VB or C# I would be much obliged?

Best Regards Peter Karlström Midrange AB, Sweden