Expected sale (resp. reservation of expected sale/monthly quotas)

Hi there, has anyone an idea how to implement reservations of monthly quotas?
It means, that I don't have an order yet, but I want to keep some quantity on stock for defined customer groups (monthly base).
Because of the WMS and FIFO, I don't want to keep it on a special location.

It should be like:

DisponibleQty := QtyOnStock - QtyReserved - QtyOnOrders;

where the customer draws his reservations at first a then the rest from the disponible quantity.

Currently it is implemented as a separate table and binded to combination of Item x CustomerGroup, but Reservation Entry table would be better.


Thx