Planning Fence Rule G

We are trying to implement a forecast and use Planning Fence Rule G so Supply & Demand Inquiry and MPS will look at the greater of forecast or customer demand.

If I have a sales order on the same day as the forecast, then Supply & Demand Inquiry reduces the Quantity Available for the forecast but not the sales order.  That is what I would expect.

If I have a sales order on a different day of the week than the forecast, then Supply & Demand Inquiry reduces the Quantity Available for both the forecast and the sales order.  I did not expect that.  I thought that if the sales order and the forecast are in the same week, then the sales order should consume part of the forecast.