Organ, 3 staff / 2 staff ?

Is there any ways to determine a 2 staff or 3 staff organ?

Or better use a 2 staff organ and a 3 staff organ according to the flow’s need ?

Thanks for advice.

At the moment, we only have a three-staff organ instrument. I guess we should probably add a two-staff version as well: I will make a note of this.

Thanks Daniel.