If you use AUM and you send Dream Foot midi out to AUM only, then you can inside AUM setup what apps the midi is sent to and you can decide which range of tones from the keyboard are sent to which app.
In AUM set ”AUM Destination” as midi source for the music app you will use: And then set what range of tones you want to go to the app:
Using this method I have created a setup for U2’s “With or Without You“ where tones below C4 are sent to a plucking arpeggio while tones above C4 are sent to a sweeping pad in a different app in AUM. And then for chords with only notes below C4 only the arpeggio will be played and in other chords I add tones above C4 also to have the sweeping pad playing. To get the right sound on the arpeggio even if only received notes below C4 are used, I have transposed the arpeggio input one octave (12 semitones) up in AUM as can be seen in the image above. Finally I have excluded the C1 note from any app meaning that I in song mode with sustain set on just can add a “chord” of the tone C1 to get complete silence without needing to toggle Sustain off (and then on again)