Honestly the Pic of the Encoders in the Wiki confuses me as it looks as if it is mis-labelled so I stopped using that as a reference since each wire has different labels on each end...

https://github.com/MMjoy/mmjoy_en/wiki/Connecting-basic-inputs-and-setting-up-software

I was thinking the output from one RC would overwhelm the next but maybe I am wrong ....likely since I am new to electronics and Joystick Conversions in General