CROATIA CRIMINAL CODE
GENERAL PART
CHAPTER FIVE (v) - PUNISHMENT AND SENTENCING
Article 62
(1)When a convict is tried for a criminal offense committed before beginning to serve a sentence as a result of a previous conviction, or for a criminal offense committed while serving imprisonment, long-term imprisonment or juvenile imprisonment, the court shall pronounce an aggregate sentence for all criminal offenses, applying the provisions of Article 60 of this Code, taking the previously assessed sentence as already fixed. The sentence, or the part of the sentence which the convict has already served, shall be included in the pronounced aggregate sentence unless the aggregate sentence is life imprisonment (Article 60, paragraph 2), point a).
Joint sentence following multiple convictions - national proceedings
EDIT.