Add PERNR field to PO Account Assignment

Dear all,

I would like to add PERNR field to account assignment K in PO. As i see in OXK1, in screen 1101 the field is there. Moreover, the field exists in RBCO and BSEG, so i would like to add it to the screen of the account assignment and append EKKN to save the value.

Does anybody knows how to change the coding block of the account assignment field and add PERNR in PO?

BR