How to use both "xsl" and "fo" namespaces together in nXML

Howdy,

I've got nXML configured such that if I edit a document "foo.xsl", the "XSLT" schema is used. 

If I enter "<xsl:" and hit C-return, then I get the expect completion prompts/action from nXML.

Likewise if I edit a document "foo.fo", then the "FO" (for XSL-FO) schema is used.

If I enter "<fo:" and hit C-return, then I get the expected completion prompts/action from nXML.

The problem I'm having is I'd like to be able to develop XSLT stylesheets that transform XML to XML-FO and
therefore would be using the XSLT schema in nXML. When I do this I cannot figure out how to configure the
relaxNG schemas such that I get  a schema that lets me have BOT "<xsl:" and "<fo:" namespaces get functional
completion working.

The smallest sample document I can show to illustrate what I mean is this one:

=====
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:fo="http://www.w3.org/1999/XSL/Format"
                version="2.0">

  <xsl:template match="/">
    <fo:root font-family="Times" font-size="8pt">

      <fo: <====== C-return HERE

    </fo:root>