The following is a serious gap in the solution:
When we forecast configured product demand, we use allocation keys to get a forecast to be managed on an option level. This option is represented by a part number that I have given a percentage.
When this part number is a phantom, the forecast consumption only works temporarily.
When my top level prod order is planned, there is an exploded demand for the phantom item in the BOM that nicely reduces its forecast.
When I firm my top level planned prod order, the phantom disappears from the BOM and the forecast consumption I had for the phantom is reversed after the next MRP.
This is entirely logical from MRP's perspective ("I see no demand for the phantom so the forecast remains unconsumed). This will lead to double demand for the components below the phantom.It really does not work.
The work around is to manually reduce all the forecasts for the items that are sitting in item allocation keys and are phantoms. And that should happen for each sale. That is a big work around.
My idea is that MRP should be changed to NOT reverse the forecast consumption when the item that carries the forecast is a phantom. that would be sufficient.