Don't know if this would be helpful for what you want to do, but something I've done in the past when I wanted multiple routings is set the speaker preferences to quad and put the multichannel sounds in the timeline, with the "use sound's internal panning" option for the track, so that it keeps whatever panning your original sound is using. The quad speaker system would have to be connected to 1-4 though, of course. Then I put the stereo sounds in other tracks, and route those tracks to outputs 7 and 8 directly, where I connect the stereo system. Outside the timeline this can be done by feeding the respective channels of a stereo sound with channellers to the inputs of an Output8 sound (with constants going to the other outputs), and mixing this with the multichannel pan in a Multichannel Mixer. Not very elegant, but seems to work. I'd love to know if there are easier ways of doing this.