Change Accounts Payable GL account on Purchase Order

Hi, I try to create a purchase order (or purchase invoice) for intercompany purchase.  One side will go to expenses account by manual selection and the other side will go to the default Accounts Payable account automatically. I wondered if I could change that default Accounts Payable account to other GL accounts on the run?  The reason is I've tried to separate all the intercompany transactions to third party vendors purchase.  Furthermore, as there have more than one intercompany within the group, I'd like to set up different Account Payable GL accounts for each intercompany. Hope someone can assist on this