Solution : https://service.sap.com/sap/support/notes/1281578 (SAP Service marketplace login required)
Key words : 
customer-specific development class, ko14valmin = xthe required function, customer-specific package, copy plan values, manual advance tasks, tab    = coom_plan_copy_year_rangefield  = cj9b, copy planning data, fiscal years individually, utility program z_t811flags_maintain, target fiscal year
Related Notes : 
       
| 672255 | Shortened fiscal year/changing fiscal periods |