I'm not sure if I understand correctly..
Do you mean sharing information when they are both running?
If so, then "References" are useful for this. I think there are examples available of vi's using references.
For instance, you have one vi running. Your other vi wants to know the progress of the first one or obtain certain values, etc. Using reference allows the second vi to get the desired data from the first vi. The vi's are not wired onto each other, both run in parallel.
If this is not what you meant, can you provide more details? I'm not sure what you meant about controls.
Regards,
JLV