I am not sure that I am interpreting section G3.1.3.14 in the correct way.
I am considering only one fan-powered box:
Qp = primary air flow (variable)
Qs = air flow relative to the fan in parallel VAV fan-powered box (constant)
Qtot = Qp + Qs (variable)

Condition 1.: Fans in parallel VAV fan-powered boxes shall be sized for 50% of the peak design flow rate
Interpretation: Qs = Qp,max / 2

Condition 2.: Minimum volume setpoints for fan-powered boxes shall be equal to 30% of the peak design flow rate.
Interpretation: Qp,min = 30% Qp,max

Are the interpretations correct?
Best Regards