Backend Source of Supply not supported for Direct Material in SRM

Hi ,

When creating S/C or PO in SRM for Direct Material , backend Source of Supply ( i..e Purchasing Info Record or Backend Contracts ) not availble to select as a sourc of supply .

In our case, we are planning to maintain the sourc of supply (PIR or Contracts) in back end MM system only , then how can pick up the same ?

Can anyone please suggest on this .

Regards

NAP