Need to procure materials even after ordered quantity as a free good

Dear Users,

I have a case like we raise PO for 100 quantity and received all the ordered quantity i.e., 100 so PO will be closed. But we still receive some more materials from same Vendor take it as 10 quantity and it should be a free goods which has no value or any PO. So my doubt is how to configure free goods for same material which has value as well as no value i.e., zero value. Please give me some possible solution.

Thanks,

Manoj