如何选择一组节点并向其添加新元素（兄弟）？

Question

我已经有了将子项附加到元素的代码。但我还没有找到一种方法来添加另一个兄弟姐妹。基本上我有一个节点列表，它们都是用字母和数字命名的。例如：A01，A02，B05，B06，D19，D20等。现在，当我想将另一个节点添加到“D组”时，到目前为止我有代码执行此操作：

Protected Sub addNodeToSectionInOrder(ByVal rootNode As XmlDocument, ByVal rowNode As XmlElement)

    Dim xmlNameTbl As XmlNameTable = rootNode.NameTable
    Dim xmlNS As XmlNamespaceManager = New XmlNamespaceManager(xmlNameTbl)
    xmlNS.AddNamespace("asp", "http://webadmin.rp.com/asp")

    Dim sectionLetter As String = rowNode.GetAttribute("ID").Substring(0, 1)

    Dim addingNav As XPathNavigator = rootNode.CreateNavigator

    Dim addingItr As XPathNodeIterator = addingNav.Select("//asp:TableRow[starts-with(@ID, '" & sectionLetter & "')]", xmlNS)
    While addingItr.MoveNext
        'just moving iterator to the last node
        'hope to find a better way of doing this
    End While

End Sub

现在我只想将rowNode添加到此列表中，作为兄弟。我试过xpathnavigator，xpathnodeiterator，xmlnodelist。到目前为止没有。我很确定我接近错了，但无法弄清楚在哪里。

编辑：示例XML

<?xml version="1.0" encoding="utf-8"?>
    <Root>
        <BoxGroup ID="A01">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="A02">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="A03">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="B01">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="B02">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="B03">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="C01">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="C02">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="C03">
            <Items>Apple</Items>
        </BoxGroup>
    </Root>

添加为全新节点：

<BoxGroup ID="B04">
    <Items>Apple</Items>
</BoxGroup>

结果XML应为：

<?xml version="1.0" encoding="utf-8"?>
    <Root>
        <BoxGroup ID="A01">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="A02">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="A03">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="B01">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="B02">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="B03">
            <Items>Apple</Items>
        </BoxGroup>
        **<BoxGroup ID="B04">
            <Items>Apple</Items>
        </BoxGroup>**
        <BoxGroup ID="C01">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="C02">
            <Items>Apple</Items>
        </BoxGroup>
        <BoxGroup ID="C03">
            <Items>Apple</Items>
        </BoxGroup>
    </Root>