The UK building regulation for Two Kite Winders Stairs: The rule for all treads says that “Twice the individual rise plus the going (2R +G) must be between 500mm and 700mm"
Believe me, before you start designing two kite corner stairs is better to do calculations. Because rule says 2 * step rise + kite going has to be between 500mm and 700mm. Stairs can't be too wide and tread rise has to be below 180mm.