Partial Goods receipt in multiple account assignment PO

HI,

I have activatedLOG_MM_MAA_1 business function. Then created Purchase order with multiple account assignment(cost center)

in single line item.

Account assignment      Material          Quantity      Plant               Loc

K                                             ABC                    10               D000          D000

Account assignment Tab

Quantity      Cost center

2                         31380019

4                         31380014

4                         31380012

how to create partial Goods receipt for such purchase order. As at the time of GRN account assignment tab is non editable. I want to select the account assignment at the time of GRN.

Regards,

Varsha