Please provide more details...
As I understood from your statement: you have a material (finished good) that you sell and maintain forecast. This selable material is produced in-house and coitains in its structure of BOM another FINI, and when you sell this another FINI, you want to reduce the first FINI remaining forecast.
Is this?
What you mean with "Dependent t requirement "at the lower level material (Material Below FG in BOM) should consume the forecast of the "Planning material."
Please provide the BOM relationship of these materials and the main MRP views of materials, please...
It's a little bit confused...
Rgds,
Marcio