Is it possible to receive multiple receipts with different item cost for standard PO

 Dear's

Can any body suggest me, "Is it possible to receive multiple receipts with different item cost for standard PO"

We are pacing standard PO for bulk purchase, but we are receiving multiple qty's in different months., but the rate is changing on item every one week, now the client wanted to receive the item with different rates, is there any possibility against that standard PO's which was already created,

Apart from above, pl suggest if any work around's.

Thanks & Regards 

M Y Giri