G\L Class code for free goods line

Hi,

How can i create a sales order with the free goods having a GL class of a parent Item without creating multiple free goods stock\NS item or multiple line types?

Ex. - Requirements -

Order # 123

Sales order details -  XXX   GL class code GL11

Free goods line  -     BBB    GL class code GL11

AS IS Condition - parent item  'X'XX'   GL class code GL11

                             Free Good  'BBB'   GL class code GL00 (this is fetched from Line type constant)

Thanks,