GL Class for Intra-Company Returns

We are setting up a process for creating intra-company return orders.  We have a doc type define that we use for Intra-company orders and we want to use the same doc type but use a different GL Class code to designate that it's a return.  The normal process for the order entry is through P4210.  That doesn't give us access to change the GL Class code.  When we enter the order the GL Class code defaults from the item branch (FG20 in our case).  We then have to go to P42101 to update the GL Class to the return GL