So, reading barricade, it mentions it creates cover in one adjacent square, and that allies adjacent to it benefit from the partial cover. So, with that in mind:
o o o o o o X o
o o o o o C C C o
Using the above where the 'o's are open squares, the 'X' is the cover and the 'C's are the characters, all three characters are benefiting from the cover?
So long as the line of effect travels through the barricade square I'm gonna say yes.