Retaining unparsed data after XML parsing/conversion

In Ultra pipelines, is there a way to retain data that wasn’t parsed by the XML parser? I would also like to retain data that wasn’t converted to XML.

Consider this example pipeline:
image

The Binary to Document1 snap output looks like this:

[
  {
    "task_name": "...",
    "content-length": "164190",
    "origin": "chrome-extension://aicmkgpgakddgnaphhhpliifpcfhicfo",
    "content": "<?xml version=\"1.0\" encoding=\"UTF-8\"?><integrationMessage>...</integrationMessage>",
    "accept-language": "en-US,en;q=0.9",
    "method": "POST",
    "query": {},
    "mytoken":"ABCD1234ABCD1234"
    ...
  }
]

I want to be able to send mytoken in the header of a later REST Post, after I’m done extracting some data from the parsed XML. Is there a way mytoken can be retained?

The other challenge I have is that the REST endpoint in question only accepts XML request body which means I need to use the convert to XML snap. The problem is that I need to pass mytoken in the request header but it shouldn’t be in the body. In my testing I found that the entire document is converted to XML by the convert to XML snap so I’m in a bit of bind.
Before Convert To XML:

[{
    "REQUEST": {
        "REQUEST_DETAILS": {
          "REQUEST_DETAIL": [
            {
              "ENTITY_ID": "123456123",
              "FIRST_NAME":"John",
              "LAST_NAME":"Doe"   
            }
			...
          ]
        }
    }
}]

The output of Convert To XML:

[
  {
    "content-type": "text/xml; charset=utf-8",
    "content": "<?xml version='1.0' encoding='UTF-8'?><REQUEST>...</REQUEST>"
  }
]

Is there a way to get something like this?

[
  {
    "mytoken":"ABCD1234ABCD1234"
    "content-type": "text/xml; charset=utf-8",
    "content": "<?xml version='1.0' encoding='UTF-8'?><REQUEST>...</REQUEST>"
  }
]

I would then be able to send mytoken in the REST Post request header.