Blending two instrument sounds into one instrument

What I want to do is create a sound somewhere between the church organ sound and the reed organ sound from the standard sound font file (most modern organs have a tonal quality that is somewhere in the middle of these 2 sounds).

What I hoped to do was create an instrument that, similar to the violins (which are comprised of 3 sounds, the main, the pizzacato, and the tremelo patches), has these 2 sounds individually mixable as desired within the mixer window.

After looking at the instrument.xml it appeared that I could do this by adding a new instrument that looks as follows:

            <Instrument id="organ2">
                  <longName>Organ2</longName>
                  <shortName>Org2.</shortName>
                  <description>Electronic Organ plus reed</description>
                  <musicXMLid>keyboard.organ</musicXMLid>
                  <staves>3</staves>
                  <clef>G</clef>
                  <bracket>1</bracket>
                  <bracketSpan>2</bracketSpan>
                  <barlineSpan>2</barlineSpan>
                  <clef staff="2">F</clef>
                  <clef staff="3">F</clef>
                  <barlineSpan staff="3">1</barlineSpan>
                  <Channel>
                        <program value="19"/>
                  </Channel>
                  <Channel name="reed">
                        <program value="20"/>
                  </Channel>
                  <genre>common</genre>
                  <genre>jazz</genre>
                  <genre>orchestra</genre>
            </Instrument>

All I changed were the values in the first 4 properties (id,names, descriptions), and added a channel named "reed", pointing to program value 20 which is the value for the reed organ sound.

Indeed, this does create "Organ2" this within the selectable instruments, and within the mixer Organ2 now provides two separately mixable instruments, one set to the "Church Organ" sound and the other set to the "Reed Organ". Unfortunately, the "Reed Organ" is non-functional ... is not making any noise.

Any suggestions?