Stacking IHM06A1

I'm hoping someone can provide a straight-forward answer as to how I can operate multiple stepper motors using stacked IHM06A1 boards. In example code, the STSpin220 class is initialised as

motor = new STSpin220(D2, D8, D7, D5, D10, D3, PWM_REF_PIN);

Is there a simple way of declaring two 'motors' in this way, perhaps with a small hardware mod?

Thanks