Yes you can.
create string or number controls how many you set, make them as Subvi's input node.
it doesn't matter what the string's name or number name's target connect it !
No. need input and output.
I suggest you that don't align it as a SubVI, it will be confuse for you !
BoyKK,
Sorry,
The SubVI which you told with me that cann't be made. cause the event occurs "mouse down event". it is focal to the solid string control, waiting for mouse down event occuring.