Hi Christian,
Thanks for your reply.
We've decided to implement badi "Validation for Actions" within delivery due to the lack of time to resolve the issue. This decision was based on note "1833378 - Prevent deletion of outbound delivery with invoice". This note gives you sample code for badi to check ERP billing status before deleting the document. We've adapted the code for our needs and it works great!
After your reply, i spent a little more time on user status, and found an OSS note that guides you trough some configuration steps on tcode /BOPF/CONF_UI. After applying this setting for business object /SCDL/FDO, the user status also worked fine!
Best Regard,
Felipe Tripodi