Stringer question

[Alok]

I wonder if somebody can help me to solve this one. Stairs in Chief are built very different to the way they are built in Australia. Chief cuts the steps into the stringers and it has one in the center to be strong enough . In OZ the stringers are straight, the steps thicker (2 inches), notched into the sides of the stringer and generally open. My problem is the central stringer, a no no where I work. Is there a way to delete or restrict the central stringer? The stair is 800 mm or about 32 inches wide. I appreciate your effort.
Alok