No, the H9’s right footswitch cannot send messages to downstream H9s. However, the way around this is using an auxiliary switch to send the CC messages to increment; the H9’s Expression Pedal, knobs and Aux Switches can be used as MIDI controllers. So, if you program an aux switch to increment, the Leader H9 can send that CC message downstream. You would need to program the Follower H9 to increment when it receives that CC# (RCV.CTL). The Leader H9’s XMT.CC has to be set to the same CC#. Also, I believe CTL.XMT must be set to ON.