turn off keyboard control (KBD CTRL) for part 2 and then it will no longer be played by the internal keys.

Thanks, with this I managed to get it working! I think I tried it before, but it seems if you select the Part by clicking on its name it will be played regardless of the setting of the keyboard control. If you click on the name of the Performance though, then the KBD CTRL settings take effect.

Yes, Kbd Ctrl depends on which Part (including none) is selected. From the home screen the selected Part can be seen as having a white box around the Part. If you've selected Parts 9-16 you may need to show that range of Parts. In order to force selecting none of the Parts one way is to press the [PERFORMANCE] (HOME) button which will deselect any selected Part. Only one Part can be selected at a time. If you edit a Part - then that Part will be selected and stay selected even if you exit the editing process unless you press [PERFORMANCE] (HOME) to ensure no Part is selected. Any time you touch a Part from the home screen this will also select a Part.

When no Part is selected (focused on piano keys only):

All Parts with Kbd Ctrl will be triggered together in a group when pressing the local piano keys. Assuming the key pressed is in the note range of the Part, the Part will sound.

When a Part is selected and that selected Part has Kbd Ctrl ON:

All Parts with Kbd Ctrl will be triggered together in a group when pressing the local piano keys. Assuming the key pressed is in the note range of the Part, the Part will sound. Yes, the same as above.

When a Part is selected and that selected Part has Kbd Ctrl OFF:

Only the currently selected Part (with Kbd Ctrl=OFF) will be triggered (again, assuming piano key is in note range of this Part). All other Parts - including Parts with Kbd Ctrl ON will ignore piano key presses meaning transitions from key OFF to key ON.

Last - if you were previously able to trigger any Part (or Parts) by the piano keys and then switched either the selection OR state of Kbd Ctrl such that you no longer trigger that Part - if you happen to hold down keys of this Part (which no longer can be triggered) - that Part will continue to sound as long as you hold down the keys. This is similar to how "SSS" (Seamless Sound Switching) works between Performances only this is in the context of a single Performance. This is often exactly why you would elect to use Kbd Ctrl instead of Mute to control which Part(s) are selected to sound. To allow for overlap.

Given the way this works - it's therefore important to ensure you pay attention to which Part is selected. Often you expect the system to work as if no Part is selected. However, when editing the Performance you are often selecting a Part with Kbd Ctrl=OFF which selects it and "messes up" your intent. I say that in quotes because it's working as intended - but you and your usage intend to never select a single Part. Therefore - be sure to deselect all Parts after editing. I personally wish there was a "strict mode" where the selected Part would not matter and only Kbd Ctrl=ON Part(s) would always sound as a group. Something I could set for individual Performances. It's a minor grievance.