Ton,
My "merge-control" is just a merge vi, as attached. However the trick was to insert it into the controls palette (insert vi, view all files, select the merged vi instead of the xcontrol). Merge VI's on the controls palatte seem to be automatically set to "explode/un merge" on use.
To explain the use, this xcontrol is used to allow interuption of logic data flow. This one is to simulate a switch that is used as an input to a PLC. Thus standard simulation logic determines the normal (simulated real world) operation and is wired to the "In" parameter. The xcontrol displays the simulation value on the front panel as the light on the left. The middle switch is to either pass through the simulation value, or use the value input to the right led button. The block panel control would then be wired out to connect to the PLC. The objective of the control is to allow simulated operation, and forced faults to fully test PLC logic. Hence I needed an xcontrol with both an input and output on the block diagram and a front panel object. As we may have over 1000 of these in a project, I wanted to eliminate having to click on the block icon, select create, property node, In, and also turn off the label (to minimise space usage).
Kent