Solution : https://service.sap.com/sap/support/notes/391220 (SAP Service marketplace login required)
Key words : 
solution create function module co_dm_doc_links_order_del, additional key words co01, reference field caufvd-aufnr, function 'read master data', function group codm, import parameter i_aufnr, attached program corrections, lower-level order, document links exist, function module
Related Notes : 
       
| 408027 | Update termination when saving the sales order | 
| 391678 | No homogeneity list after conversion of planned order | 
| 381237 | Object links for production orders |