Syncronizing between many instruments

[freewind]

Hi All,

I'm working on a strategy that load many instruments(~100) and do some checking to enter a position on bar close in OnBarUpdate().
I want to do the check only once so I have:

 if (BarsInProgress != 0)
                return;

I know that NT is event driven so my issue is what happens if some of the instruments trades less frequent then the BarInProgress == 0 or vice versa, what data I'm referring to in the call for OnBarUpdate() when I'm using for example Closes[50][0]?

I hope I made my question clear :-)
Tx in advance!