Sub main()
    Dim xml As MSXML2.DOMDocument60
    Dim sb$
    Dim xNode As IXMLDOMElement
    Dim xRoot As IXMLDOMElement
    Set xml = New MSXML2.DOMDocument60
    sb = Chr(62) & vbNewLine & Chr(60)
    xml.appendChild xml.createProcessingInstruction("xml", "version='1.0' encoding='utf-8'")
    Set xRoot = xml.createElement("Document")
    xRoot.setAttribute "xmlns:xsi", "http://blabla/2001/blablabla"
    xRoot.setAttribute "xmlns:dtr", "http://blabla.ru/blabla/blabla"
    Set xNode = xml.createElement("Rows")
    xNode.appendChild xml.createElement("row")
    xNode.appendChild xml.createElement("row")
    xNode.appendChild xml.createElement("row")
    xRoot.appendChild xNode
    xml.appendChild xRoot
    xml.LoadXML Replace(xml.xml, "><", sb)
   MsgBox xml.xml
End Sub

<?xml version="1.0"?>
<Document xmlns:xsi="http://blabla/2001/blablabla" xmlns:dtr="http://blabla.ru/blabla/blabla">
    <Rows>
        <row/>
        <row/>
        <row/>
    </Rows>
</Document>

<?xml version="1.0"?>
<dtr:Document xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dtr="http://blabla.ru/blabla/blabla">
    <dtr:Rows>
        <dtr:row/>
        <dtr:row/>
        <dtr:row/>
    </dtr:Rows>
</dtr:Document>

Sub main()
    Dim xml As MSXML2.DOMDocument60
    Dim sb$
    Dim xNode As IXMLDOMElement
    Dim xRoot As IXMLDOMElement
    Set xml = New MSXML2.DOMDocument60
    sb = Chr(62) & vbNewLine & Chr(60)
    xml.appendChild xml.createProcessingInstruction("xml", "version='1.0' encoding='utf-8'")
    Set xRoot = xml.createElement(getNS & "Document")
    xRoot.setAttribute "xmlns:xsi", "http://blabla/2001/blablabla"
    xRoot.setAttribute "xmlns:dtr", "http://blabla.ru/blabla/blabla"
    Set xNode = xml.createElement(getNS & "Rows")
    xNode.appendChild xml.createElement(getNS & "row")
    xNode.appendChild xml.createElement(getNS & "row")
    xNode.appendChild xml.createElement(getNS & "row")
    xRoot.appendChild xNode
    xml.appendChild xRoot
    xml.LoadXML Replace(xml.xml, "><", sb)
    MsgBox xml.xml
End Sub

Function getNS()
    getNS = "dtr:"
End Function