I looked in the settings but didn't see anything related. Allies in the way block line of sight and prevent shooting.

Now, obviously, this is a good thing, most of the time.

I had three guys ready to fire on a pirate who had just taken cover around the corner of a building. They could see each other just fine, as the pirate was firing at them. I had fire at will turned on, and even manually told them to shoot the guy, but they all just stared at me with that dumb look on their faces until the pirate shot one of their kidneys out because a chicken was wandering through.

The instant I told one of them to shoot the chicken dead they're all like oh, hey, there's a pirate here! Hen 219 died :(

... although after typing that number I realize that, more than anything, I have a chicken problem.