Question on Item Allocation Key

Question on Item Allocation Keys: You attach an Item Allocation Key to an Item Group by navigating the following path By definition, Item Allocation Key is the % age break up of a forecasted Sales or Purchase quantity of all the item’s included in the Item Allocation Key. We can set up the Item Allocation by navigatin through the following menu. Item Group->Click on the Forecast button->Select Sales or Purchase and then attach the Item Allocation Key to the line. In the line we specify the forecasted Sales Quantity which is broken down as per the percentages mentioned for the items mentioned in the Item Allocation Key. If all the items in the Item Group are included in the Item Allocation Key then there is no issue. But it could very well happen that the Item Group could consist of a few items that are not included in the Item Allocation Key. In such a situation from a forecast planning perspective how would Axapta treat such items. Or it could also happen that all the items included in the Item Allocation Key may not belong to the Item Group at all? Again, in such a situation how does Axapta react.