If you don't mind an analogue/non-midi solution, maybe a 1980s Morley SLMC-4 would fit the bill. It has four mono inputs and four mono outputs. If I understand your question, it could take your stereo outs as two mono lines, your organ out and you would have one more input/output left over.
I have one myself. Like my other Morley pedals, it was a reliable and solid piece of gear at a time when my setup was a bit more modular. Though it currently sits in semi-retirement, I do want to hang on to it for a while longer. I see that Reverb.com has had some of these for sale in the past, so if it looks like what you need, you might want to start looking.