Hi DonM,
I personally don't have a need for "midi merge" but it is my understanding that fellow Synthzone board member Tonkan wants this feature. He wants to be able to take the original midi source data entering his keyboard (at the "midi-in" port) and to MERGE this data with the midi data created on his keyboard and then send this "merged" midi data out thru the keyboard's "midi-out" port.

Clif had thought this is possible (without having to purchase an external midi-merge box) on the higher-end Yamaha PSR boards.Please check your PSR keyboard and let us know if there is some kind of midi setting feature which would allow you to turn "midi merge" on/off? As far as I know, this would be the only way to find out if the Yamaha PSR keyboards support an internal midi-merge feature function. If the PSR keyboards don't include this type of setting then the only way to perform the type of midi merge function Tonkan desires is by connecting an external midi merge box to both the "midi-out" and "midi-thru" ports on his keyboard.Curious to hear your finding.
-Scott