NL4 and external knobs for CC

[SamBooko]

Hi guys!
I want to control the output knob of every slot separately with the knobs of a keystep pro.
BIT I use the slot A and B on the same midi Channel (1) and C and D on channel 2.
If I set up the midi CC (71) of the knob 1 on channel 1 it controls BOTH slot A and B but I want it to be controlled separately!
For other reasons that are too complex to explain here I don't want to change the midi Channel of slot B and D because I need them to be on the same channel.
Are there ways to keep the same channel of slot A but receive the CC of the output in a way that doesn't control both of the slots parameters?
Thank youu