I'll try to explain the question the best i can (sorry for the english!)
I have Wolves and Sheeps
Wolf LoS considers Sheep as obstacle, so he won't see behind her.
Wolf also attacks sheep if she is in LoS, and since she's an obstacle herself, she will never be in LoS.
Is there a way to allow LoS obstacle to be seen by the very same LoS behaviour they're an obstacle to?