If you find a wheelbarrow, only your character and one other member of your squad is able to"attach" to the vehicle. Do that and the other three guys mill around. Since they are no longer part of your squad, it is possible to call down more reinforcements. Once your squad is full again, you can repeat the "discharge" process with the wheelbarrow and call more men down.Note: ordering too many soldiers (around 70 to 80) will slow the game and may even freeze it. This works in online and offline modes.