You don't actually need to pass anything to the Sub-VI.
Within the Sub-VI you can call up the chain of "higher" VIs, i.e. the VI call chain leading to the sub-VI in question being called. From here you can wire simply the text of the VI you require to an "Open VI reference" function, get a list of the controls or indicators and initialise them as you wish. I used this a few times for a custom "Print Parent Panel" VI.
Here's a pic of an example (LV 6.1)
Hope this helps
Shane.
Using LV 6.1 and 8.2.1 on W2k (SP4) and WXP (SP2)