I would suggest that this will depend on the midi command.
The midi command needs to be something that can be incorporated into a 'User Performance' on the BK-9, and I'm not sure if that is possible. Then, when the UP is invoked on the BK-9, this device needs to send the data (maybe using a specific channel) in such a way that the Controller will receive it, and can act upon it, but this command will not interfere with anything else. This may depend on how the devices are connected together, and what else is connected inbetween.
Geoff