How can I process child nodes the same way as parent nodes using multiple files as input in XSLT?

I am currently trying to process multiple files for specific nodes and collect them in a meaningful way to demonstrate the parent-child relationship but I'm having trouble getting past the first level of children.

A little background:

I'm attempting to collect procedure codes from a service manual. The manual is composed of several XMLs. The procedures these codes refer to sometimes refer to subprocedures, which in turn may refer to subprocedures. I want to list out all the procedure codes. If there is a subprocedure referenced in a procedure, I want to list its code as a child and continue in this way for all subprocedure until a procedure is listed that does not include a subprocedure.

Something like this:

<service-manual>
  <procedure>
     <name>Procedure A</name>
     <frt-num>1234</frt-num>
     <child-proc>
        <frt-num>2345</frt-num>
        <child-proc>
           <frt-num>3456</frt-num>
           ...
        </child-proc>
        <child-proc>
           <frt-num>4567</frt-num>
           ...
        </child-proc>
     </child-proc>         
     ...
  </procedure>
...

However, the result that I'm getting from my style sheet is only processing the first set of children.

The style sheet I've developed looks like this:

<xsl:template match ="directory">
    <service-manual>
        <xsl:apply-templates select="file"/> 
    </service-manual>        
</xsl:template >

<xsl:template match="file">     
    <xsl:variable name="path" select="@name"/>
    <xsl:for-each select="document($path)/*">
        <xsl:for-each select="/*">
            <procedure>
                <name>
                    <xsl:value-of select="title"/>
                </name>
                <frt-num>
                    <xsl:value-of select="substring-after(@id,'X')"/>
                </frt-num>                    
                <xsl:apply-templates select="//cmd"/>
            </procedure>
        </xsl:for-each>
    </xsl:for-each>
</xsl:template>

<xsl:template match="//cmd">
    <xsl:for-each select="xref">
        <child-proc>
            <frt-num>
                <xsl:value-of select="substring-after(@keyref,'X')"/>
            </frt-num>                
            <xsl:apply-templates select="file"/>
        </child-proc>            
    </xsl:for-each>
</xsl:template>

Obviously, this is wrong. My thought was that I should create a template that processes the xref nodes and then call that template from the //cmd template but that didn't work much better. Is that the direction I should be taking with this? Also, is using modes an option here? Being that I'm a bit of an amateur, the logic involved with successfully accomplishing this has my brain twisted up a bit. Any help appreciated.