I dont fully understand your setup.
Other than the two switches on the H9.. how many switches do you have? Is anything plugged into the side of the Barn?
If I were you, I would use the main Barn 3 switches to increment.. use the H9’s ACTIVE switch to activate, the H9’s TAP switch for tempo.. and plug in an additional AUX switch on the Barn to add a FLEX switch.
Unless you dont need tap tempo.. then I would use the right side barn for down, the right side H9 for up, and the left barn for Flex.