I don't know anything about COM, but if it is a normal variable (even if it is global), then you can always:
alt + 2 to open the viewport and enter the name of the variable there, for example
blahblah.dll! Reference
You will need symbols for this, you may also need to be in source mode. This is slightly better than dv / dt, as you do not need to enter it constantly. I also think you can enter the address. Please note that if you do not put the blabbal! then it can sometimes cause windbg to stop for a few seconds when it searches for each module for something called guid.
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