FAC without line-of-sight

[AVZ]

Is there anyway that I can make it so that a particular FAC can do 9-lines for a particular enemy group in an area - regardless of whether it has line-of-sight or not. I thought that "FAC Assign group" was suppose to do that... it doesn't seem to be the case at all. What is the FAC Assign group best used for anyway?

 

Thanks in advance!