Help with parsing XML content

Elastic Stack Logstash
3

OK, I've switched to xpath. Logstash is now successfully parsing out the values I need, but they are not present in my Document after successful run... How can I add the four new fields to my doc? A short example would be perfect.

Here is my config:

filter {
  if [path] =~ "SLIC" {
        mutate { replace => { "type" => "slic" } }
  } else {
        mutate { replace => { "type" => "sysout" } }
  }
  grok {
    match => [
          "message",
          "^\[%{DATESTAMP:tslice}\] %{GREEDYDATA} HttpClient.submit - POST : %{GREEDYDATA:inxml}"
    ]
  }
  if "_grokparsefailure" in [tags] {
          drop { }
  }  
  xml {
      source => "inxml"
      target => "xmldata"
      store_xml => "false"
      xpath => ["/BillingAndCosting/ControlArea/SenderId/text()","senderid"]
      xpath => ["/BillingAndCosting/ControlArea/WaterMark/text()","watermark"]
      xpath => ["/BillingAndCosting/ControlArea/RecordCount/text()","nbrofaccounts"]
      xpath => ["/BillingAndCosting/ControlArea/TimeStamp/text()","timeofdelivery"]
  }
}

Also, is there a way to count nodes that may appear in the XML structure, like in this example below. How can that be reflected in the config file?!

  <xsl:for-each select="BillingAndCosting/DataArea/CustomerAccount">
    <p> Account <xsl:value-of select="ExternalKey" /> has <xsl:value-of select="count(BillingData)"/> invoices</p>
  </xsl:for-each>