reverb level control via MIDI

Hello. I'm using qsynth 0.5.0 and this function doesn't seem to be implemented. The GUI reverb control works but doesn't respond to CC 91 messages. All I would like to do is have different reverb levels for a couple of different instruments (on different channels), and it's too cumbersome to change the GUI control quickly. I thought about having a different fluidsynth instance for each instrument, with a different amount of reverb set, but as I understand it all the fluidsynths will receive the same messages so they would all sound on all channels. I would have to find a silent/dummy instrument to select for the channel(s) I don't want to sound. Or I might have to resort to using fluidsynth directly, which does respond to CC 91. There must be a better way! Many thanks.