In the demand charge structure I describe:
If the peak demand for a given month occurred at 2 pm, then the $16/kW rate would apply, so if the peak in the period 11 am to 7 pm was 400 kW for that month, the demand charge for that period would be 400 kW * $16/kW.
Then, if the peak in Period 2 (outside of the 11-7 period) was 600 kW, the $4/kW rate would apply, and the total demand charge for the month would be the sum of the two.
I think what you are saying is that the two periods overlap, so that the $4/kW rate might also apply to a demand peak that occurred in the 11-7 period.
I think you can model that by using the Demand Rate by Month with Optional Tiers for the "Deliver" rate (set the charge for all months to $4/kW), and defining the Demand Rates by Time of Use Period and/or Tiers as I describe above for the "Power Supply" rate, except set the charge for Period 2 to zero.
Using that method, if the peak demand happened to occur during the on-peak period, then both demand charge rates would apply.
Best regards,
Paul.