Single voice coil

Solution
That is the only way you can use all three woofers.
When you wire them in series you reduce the damping factor in the amp so the bass won't be as tight. You also decrease the power slightly at 3 ohms. What this means it that it might sound better with two woofers and not play much lower in volume either. You can try it and judge the result.
The 2 ohm rating on the amp is a minimum. Loads higher than 2 ohm would be fine. So you could wire the three subs in series to create a 3 ohm load.
 
That is the only way you can use all three woofers.
When you wire them in series you reduce the damping factor in the amp so the bass won't be as tight. You also decrease the power slightly at 3 ohms. What this means it that it might sound better with two woofers and not play much lower in volume either. You can try it and judge the result.
 
Solution