Solution : https://service.sap.com/sap/support/notes/320182 (SAP Service marketplace login required)
Key words : 
additional key words ck11, cost estimate, material master, assembly scrap, valuated bill, field 'scrap', alternative items, usage probability, implement note 115011, solution implement
Related Notes : 
       
| 115011 | CK11: Usage probability for alternatives |