Doubt in MRP

In my company, we uses the discrete manufacturing because the average cost. And we have several bills of material with returnable items to stock. That is, I order a semi finished product inventory and return some items of this semi finished product for the stock. My problem is that when I run the MRP, he does not see the return of these items. He only sees items consumed for the production of semi finished products. Thus, the MRP suggested me a huge amount of components that I do not need to buy. Has somehow to make MRP sees the return