Solution : https://service.sap.com/sap/support/notes/451848 (SAP Service marketplace login required)
Key words : 
rule-based atp check, crm solution coding change, sales order crm, terms crm order, rba main item, quantity change, item reason, quantity field, prerequisites execution, notreplicated
Related Notes : 
       
| 442332 | SAPKU30006: Support Package 6 for EBP 3.0/CRM 3.0 |