BOM & MRP - Choice of the component

Hi Gurus,

I have a question relative to the use of the alternative item group in a BOM:

We have the following need :

We have the BOM A (with several levels). This BOM is composed of component B and component C.

The component C can be produced from component C1 -OR- component C2.

We don't want the MRP to make the choice between C1 and C2 following a strategy and so on.

It's the user who takes the decision following several business rules before the MRP run (price of the material...).

How can we implement this basic behaviour ?

Thks