B3-X upper and lower manual question

I’m finding myself having to create a rackspace in which I need to utilize both the upper and lower manuals of B3-X. My controller is a Nord Stage Compact. So far, I’ve got two instances of the Nord Stage MIDI In in the rackspace. One MIDI In is outputting to the upper manual set to channel one. I also have set up a split point as well. The second Nord Stage MIDI In is set to channel 4, with a split point also set up.
B3-X MIDI is set to channel 1 for the upper manual and channel 4 for the lower. So far this is all working as expected. What I need to do now is be able to control the upper and lower drawbars individually from the Nord Stage. If anyone is familiar with the Nord Stage, there are two panels that I can set up individual MIDI output channels. My Nord program has both panels activated with one panel outputting MIDI channel 4 and the other MIDI channel 1. However, the way I have this all configured at the moment, when I select the panel that is set to output channel 4, the drawbars that are responding in B3-X are the upper manual ones. In fact, both panels are controlling the upper manual. My question is what do I need to do to have the lower set of drawbars respond to my Nord program? Is this something that I need to address on the Nord, or in my rackspace?

In my opinion, you should neither set different channels on your Nord controllers nor define splits there, but keep they as generic as possible and to the job at the GP side. And use Rig manager for… everything. Define an UpperKey MIDI alias for the upper Nord, a LowerKey for the lower Nord and also define all controls of each keyboard in Rig manager. e.g. SliderUp1, SliderUp2… SliderLow1, SliderLow2 or whatever.

The idea behind this is to avoid using MIDI for controlling the B3X drawbars, but rather host automation. This is generally the right way to do it in GP. Arrange two sets of organ drawbar widgets (drag an organ drawbar widget by maintaining 9 and GP will arrange it automatically for you) and for each drawbar widget MIDI learn the proper Nord controller and map the widget to the corresponding B3X drawbar plugin parameter.