Solution : https://service.sap.com/sap/support/notes/68303 (SAP Service marketplace login required)
Key words : 
client-specific user exit, additional account assignments, additional account assignment, delivered formpool rggbs000, reversing interest postings, special purpose ledgers, posting interest received, default cost center, stored cost center, validation/substitution maintenance
Related Notes : 
       
| 398983 | Information: IM (Investment Management) | 
| 388139 | Subtitution of trading partner business areas in FI | 
| 178573 | Activation of validations | 
| 48121 | User Exits in Validations/Substitutions |