One could probably program that into a Behringer FCB I'd reckon. It does use the only available MIDI port though, and then one would need to use the thru options (ie keyboard to FCB to BK.
Not recommended for the split second midi-clock timing required to trigger chord changes.
But it could work.
Not sure what you are getting at there, Dennis. The FC-7 does NOT use a MIDI port (it has its own dedicated nine-pin DIN input). And, I don't THINK I can remember a Roland arranger with the ability to turn Melody Intell on/off with a MIDI command (can you?).
About the only way I think you could do this at the moment is to set up UPG pairs, with one with Mel/Intel on, and one with off, and then use UPG up/down as a way to enable/disable it.