Reference of Contract for an FOC document type

Dear all,

I have a scenario where i create a Contract with value, then for that contract if needed i send materials in FOC, so when you check the copy contral we can assign the contrac to FOC sales order document type.

when when i really create the FOC order with reference to Value contract it does not allows, as because the sale document is have reference mandatory option only for Quantity contract to be copied or referenced for a sales order,

so any suggestion for acheiving the same.

Thanks

Sudhir