Template Subprocessing

So we have a small configuration for leveraging FreeMarker to produce the XML
payload of SOAP messages.  Works great.  Now we're trying to call a service that
wants to have part of the document base64 encoded.  The encoded content is also
XML that needs to be created using data from the model.

Unfortunately, I cannot change the service to make it less dysfunctional, so the
encoding is required.  I'm also somewhat constrained as to how FreeMarker is
invoked, so I can't process it all in code.

Maybe I'm dreaming, but:
Has anyone seen anything like this before?
Is there anyway to build all this into one template?  
Is there an easy way to get the results of processing a sub-template into a
string in the primary template (which I could then call out to Java to get
base64 encoded)?

My last questions seems like a straightforward way to do it, but most of the
code I've looked at returns the included/parsed files in the output and not in a
string.  Am I missing something?


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