Help with using Gridview to save data in XML file

Hi,

I have many questions on how to solve an issue, below are my following questions:

After I loading the grid with my Donorxml file.
1. How do I only add data in the grid if it doesn't already exist in Donor.xml? (If it does use the existing data to avoiding adding duplicate data)
2. If the data i enter in the grid is new, how do I save it in Donor.xml with a new ID?
3. When I select multiple rows in the grid and press Save, how do i save the IDs of the rows selected to my link.xml file
For  example when I enter:
BEL
CAN
USA
In Grid1 ( three rows of data)
I need to save them in Donor.xml  while I create new IDs as shown below:
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Root>

  <Donor>

    <DonorID>1</DonorID>

    <Name>BEL</Name>

  </Donor>

  <Donor>

    <DonorID>2</DonorID>

    <Name>CAN</Name>

  </Donor>

  <Donor>

    <DonorID>3</DonorID>

    <Name>USA</Name>

  </Donor>

</Root>

And  at the same time save the newly created IDs to one record in my Link.xmk filke

  <Link>

    <LinkID>1</LinkID>

    <DonorID>1,2,3</DonorID>

  </Link>

 

How do I modify the code to use a grid for multiple entries and saving their IDs to link.xml?

Code: (This code works for entering a single country in a textbox and saving it to Donor.xml and it's ID to Link.xml, as mentioned, now I need to be able to save multiple IDs in Link.xml after selecting multiple rows in a Grid)

 

'Donor

        Dim MyDocDonor As XDocument = XDocument.Load(Application.StartupPath & "/Donor.xml")

        Dim LargestDonorID = (From el In MyDocDonor.Descendants("Donor") Select CInt(el.<DonorID>.Value)).ToList

        LargestDonorID.Sort()

        Dim CheckForItem = (From el In MyDocDonor.Descendants("Donor").Elements("Name") Select el.Value).ToList

        If Not CheckForItem.Contains(Me.TextBox1.Text.ToString) Then

            Dim xNew As XElement = New XElement("Donor")

            xNew.Add(New XElement("DonorID", (LargestDonorID.Last() + 1)))

            xNew.Add(New XElement("Name", Me.TextBox1.Text.ToString))

            MyDocDonor.Root.Add(xNew)

            MyDocDonor.Save(Application.StartupPath & "/Donor.xml")

        End If

        'Link

        Dim MyDocLink As XDocument = XDocument.Load(Application.StartupPath & "/Link.xml")

        Dim LinkID = (From el In MyDocLink.Descendants("Link") Select CInt(el.<LinkID>.Value)).ToList

        LinkID.Sort()

        Dim xNewLink As XElement = New XElement("Link")

        xNewLink.Add(New XElement("LinkID", (LinkID.Last() + 1)))

        xNewLink.Add(New XElement("DonorID", (LargestDonorID.Last() + 1)))

        MyDocLink.Root.Add(xNewLink)

        MyDocLink.Save(Application.StartupPath & "/Link.xml")

Thanks,

Victor