Using BAPI_PO_CREATE to create a PO with reference to another PO/item

Hello,

I am trying to use the BAPI_PO_CREATE to create a PO with reference to another PO/item.  So far I have not found a way to make this work.  I can see that you can do this in ME21, but not sure if the bapi can do this too.  We are in 4.6C, so I have to use this bapi instead of BAPI_PO_CREATE1.  Any help would be appreciated!

Thanks!

Kristina