Phantom items and MRP

Hi,

Could anyone give me some pointers on MRP and phantom items.  Occasionally demand does not blow through the phantoms to the lowest level. We do not get pegging records.   We have a parent item with a phantom in the bill, that phantom has a phantom in it's bill, that second phantom has a purchased part in it's bill.  The parent items demand is not going through to the lowest level item.  We have bill integrity running and it runs at night.  We don't want to turn on generating time series and messages for phantoms unless it is a sure solution.