Hello. Since info-labview is down, I'll try this forum out.
The new subpanel control must be unique in the sense that it is not represented by a node on the block diagram. This has one funny consequence:
If you select "Hide control" and then delete the invoke node, there is virtually no trace of it at all. You could link a property node to it and make it visible that way, but you'd never be reminded that it's there. A potential source for hard-to-track bugs?