Did you know that you can manually choose the audio I/O for each individual plug-in loaded in PatchWork? This can be used to setup side chain inputs for plug-ins that may not detect or support it right away.
Here is an example in Reason 11 with some plug-ins that do not get the side chain input automatically:
Izotope’s Neutron 3 sidechain by default does not work within Reason 11 (despite the additional audio in being illuminated). Using Blue Cat’s Patchwork to load it as a VST3 or AU by default doesn’t work initially either. You have to change BC’s default audio in and out to 4 in / 2 out (loads as 10 in / 8 out) to get it working. Sidechain with Reason 11 and Neutron 3 now works.
Note this works for Waves plugins and many other manufacturers as well that don’t support VST side chaining.