well, I don't know if it is a glitch or not, but in level 2 of american campaign, i was able to put a machine gun squad, and a riflemen squad in the same cover.
I can see already that you put a LOT of work onto this game. I only played this game for 3 or 4 days. I suggest you should add a couple more maps for your bigger updates. My other suggestion is adding more cars. Plus I agree with fangyfangs. Plus I know of the secret map, but, would you please add some more maps for this game? But, I got to say, awesome work. Thank you for your understanding.